High-end Socket AM3 chipsets under the microscope

AMD’s Phenom processor had a rough first year and a half. The CPU debuted with a troublesome TLB erratum and lower-than-expected clock speeds, ruining the coming out party for AMD’s quad-core architecture. Competition was stiff, as well, with Phenoms facing off against a formidable lineup of Core 2 processors that were just hitting their stride with a new 45nm Penryn core. Even the fastest Phenoms available were no match for the best Core 2 Quads, forcing AMD to cede the high end of the market to Intel. AMD still had flagship CPUs, of course, but they’ve effectively been flying at half-mast ever since.

The lack of high-margin, high-end desktop processors may have hurt AMD financially, but it hasn’t necessarily been a bad thing for enthusiasts. We may covet ultra-expensive CPUs like Intel’s Extreme Editions, but we’re far too frugal to shell out a grand or more for what is ultimately a modest bump in clock speed. We’re more inclined to seek out the best bang for our buck, which usually means picking from the mid range and overclocking a little.

AMD’s current top-of-the-line CPU, the Phenom II X4 955 Black Edition, fits nicely into the middle of the market with a street price of under $250. The 955’s performance and power consumption are competitive with Intel’s previously unflappable Core 2 Quads, whose LGA775 socket is now all but a dead end as far as upgrade paths go. The 955 Black Edition is also cheaper than the most affordable Core i7, and it has an unlocked multiplier that makes for easy overclocking with even the most basic of motherboards.

But you don’t want just a basic motherboard for a CPU like the 955. If you were really looking to cut corners, you’d have probably settled for a dual- or triple-core CPU. Fortunately, high-end Socket AM3 motherboards cost a lot less than one might expect. Asus’ M4A79T Deluxe is based on AMD’s finest core-logic chipset, the 790FX, yet it sells for less than $190. Even more affordable is the M4N82 Deluxe, which uses Nvidia’s top-end nForce 980a SLI chipset but can be had for less than $165.

Apart from pulling from different core logic camps, Deluxe flavors of the M4A79T and M4N82 are actually quite similar. Naturally, that raises the question: is the M4A79T, with its 790FX chipset, worth a $25 premium over the M4N82 and its nForce MCP? Let’s find out.

Dueling core logic

If AMD’s 790FX chipset sounds familiar, that’s because it’s been around since November of 2007. Originally introduced for Socket AM2, the 790FX has since been updated to support Socket AM3 CPUs. The south bridge component has also been upgraded from the SB600 to the SB700 and, more recently, the SB750. These tweaks haven’t dramatically altered the 790FX’s capabilities, though—it’s essentially the same core logic package as a year-and-a-half ago.

Nvidia’s nForce 980a SLI sounds like a fresher product. After all, it has 200 more, er, nForces than the green team’s previous high-end chipset for AMD processors, the nForce 780a SLI. However, the 980a is new in name only. It’s the same silicon as the 780a, now with a BIOS update to support Socket AM3 CPUs. Nvidia says it changed the chipset’s model number to “clearly convey support for AM3 and DDR3,” never mind that Phenom memory support is determined by the processor’s on-die memory controller rather than the chipset or that Socket AM3 processors will happily plug into Socket AM2+ motherboards.

The nForce 780a SLI was released in May of last year, which makes the 980a’s roots a little fresher than those of the 790FX—not that it matters much. Both adhere to the same HyperTransport 3, PCI Express 2.0, Serial ATA 3Gbps, USB 2.0, and “Azalia” high-definition audio specifications. The nForce does differ by its inclusion of a DirectX 10-class integrated graphics processor, though. This so-called motherboard GPU has the same architecture as what you’ll find in a desktop GeForce 8400 GS, complete with a 500MHz core clock and 16 stream processors running at 1.2GHz. The 980a’s mGPU also has a PureVideo HD video block capable of decode acceleration for MPEG2, VC-1, and H.264 high-definition video content.

The 980a’s integrated graphics component may allow Nvidia to pad its GPU shipment numbers, but I don’t see the mGPU bringing much value to a high-end chipset that will all but certainly be paired with a reasonably powerful discrete graphics card. With Nvidia’s promising HybridPower tech dead on the desktop, there’s really nothing for the motherboard GPU to do anymore. Asus evidently agrees, because the M4N82 Deluxe essentially ignores the 980a’s integrated graphics component.

AMD 790FX Nvidia nForce 980a SLI
Processor interface 16-bit/2GHz HyperTransport 16-bit/2GHz HyperTransport

PCI Express 2.0 lanes
38 35

Multi-GPU support
CrossFire SLI

Chipset interconnect
PCIe 1.1 x4 PCIe 2.0 x16
Interconnect bandwidth 2GB/s 16GB/s
Serial ATA ports 6 6
AHCI Y Y
Native Command Queuing Y Y
RAID 0/1 Y Y
RAID 0+1/10 Y Y
RAID 5 Y Y
ATA channels 2 2
Max audio channels 8 8
Audio standard AC’97/HDA HDA
Ethernet N 10/100/1000
USB ports 12 12

Multi-GPU configurations made up of multiple discrete graphics cards are far more common in the systems targeted by the 980a and 790FX. The 790FX has a total of 38 PCI Express lanes to spare, all of which stem from the chipset’s north bridge component. CrossFire support is a given, of course, and the 790FX can even split its PCIe lanes between four x8 links to facilitate exotic four-way configs.

The nForce 980a divides its 35 PCI Express between the chipset’s MCP component and its nForce 200 SLI chip. Three PCIe lanes primed for auxiliary peripherals and expansion card slots branch out from the MCP. The remaining 32 lanes hang off the nForce 200 and can be arranged as a pair of x16 links or in an x16/x8/x8 config for three-way SLI.

A 16-lane PCI Express 2.0 link connects the nForce 200 with the MCP, providing 16GB/s of bi-directional bandwidth and introducing a potential choke point for graphics performance. However, Nvidia is quick to point out that the nForce 200 contains a couple of features designed to make better use of the available bandwidth. The chip supports a posted-write shortcut that allows commands to be passed between graphics cards without hitting the CPU or main memory. Also, a broadcast function is capable of replicating commands sent to one graphics card across multiple cards, reducing the burden on the CPU and the MCP/nForce 200 interconnect.

Differing approaches to PCIe connectivity aside, the 790FX and 980a have nearly identical peripheral payloads. Both sport six 3Gbps Serial ATA ports with RAID functionality, and each has a couple of “parallel” ATA channels. You get a dozen USB ports with each chipset, too. However, the nForce has an integrated Gigabit Ethernet controller, while the 790FX lacks a networking component. Motherboard makers have to rely on third-party chips to bring GigE to the 790FX.

Asus’ M4A79T Deluxe motherboard
790FX in the flesh

Manufacturer Asus
Model M4A79T Deluxe
Price (Street)
Availability Soon

At $190 online, the M4A79T Deluxe looks to be the most expensive Socket AM3 motherboard on the market. Despite the Deluxe moniker, though, the M4A79T is a surprisingly restrained affair.

One often sees supposed enthusiast boards lit up like Japanese Dektora trucks, rippling with more Serial ATA and Gigabit Ethernet ports than even we’d consider sensible and strapped to exotic cooling solutions only the most extreme overclockers actually need. That doesn’t say enthusiast to me; it screams Pimp My Motherboard, which really isn’t my style. Maybe I’m old school, but I prefer to see motherboards drop the excess and just do the basics well. That seems to have been Asus’ goal with the M4A79T Deluxe.

The M4A79T’s understated appearance suits the board’s nature. The slots and ports are color-coded intelligently but not garishly, and the dark brown board sports copper-colored heatsinks that blend nicely into their surroundings.

I’m not crazy about the brownish color scheme, but at the same time, I’m not that concerned with a motherboard’s appearance. Case windows seem to have gone out of style, and most folks run their systems out of view under a desk, anyway. The M4A79T’s layout is far more important, and Asus has done a masterful job with it, no doubt aided by the board’s relative lack of extraneous peripheral chips and ports.

The area surrounding the M4A79T’s CPU socket looks a little more crowded than it actually is. Rows of capacitors and chokes flank the socket on one side, but they’re not tall enough to get in the way. The board’s PWM and north bridge heatsinks have a little more height. However, they’re set back from the socket and didn’t cause us any problems.

Like most Phenom boards, the M4A79T’s DIMM slots—in this case, the DDR3 variety—snug right up to the socket. This arrangement can create clearance conflicts between extremely large aftermarket coolers and tallish memory modules. We managed to squeeze a massive Scythe Ninja onto the board along with some Corsair Dominators without issue, though.

The board features a modest array of storage ports, including edge-mounted IDE and Serial ATA connectors that leave plenty of room for longer graphics cards. Three of the M4A79T’s SATA ports are mounted face-up on the board, but they’re positioned to avoid interfering with two-way CrossFire configurations.

The M4A79T Deluxe also features onboard power and reset buttons. These are a nice touch for reviewers and for general troubleshooting, but I’d much rather have a CMOS reset button, either right on the board or preferably in the rear port cluster.

The M4A79T’s most Deluxe feature is easily its stack of four PCI Express x16 slots. You only get eight lanes of bandwidth running to each in a four-way CrossFire config, but with gen-two PCIe, that’s still 8GB/s of bidirectional bandwidth per slot.

In a nod to those with older expansion cards, the M4A79T features two standard PCI slots. One of them will be blocked by a double-wide graphics card installed into the primary PCIe slot, though. I should also point out that PCI Express slots are backward compatible; the board’s physical x16 slots can accommodate x8, x4, and x1 expansion cards.

Asus brings a little something for everyone to the M4A79T’s port cluster. Even the PS/2 mouse port has returned, presumably for the KVM-switch crowd, since I can’t think of a single PS/2 mouse worth using. Along with half a dozen USB ports, the cluster sports an eSATA port piped up from the south bridge, Firewire fed by a VIA controller, and Gigabit Ethernet powered by a Realtek chip.

Realtek silicon also performs audio codec duties behind the board’s analog audio jacks and dual S/PDIF outputs. The codec in question is an ALC1200 that has thus far only appeared on Asus motherboards. However, the chip appears to be little more than a re-badged ALC888, which is really nothing special. Realtek’s high-end ALC889A is the codec you want, if only for its Soundstorm-esque real-time Dolby Digital Live encoding capabilities.

Asus’ M4N82 Deluxe motherboard
The only nForce 980a in town

Manufacturer Asus
Model M4N82 Deluxe
Price (Street)
Availability Soon

The M4N82 Deluxe is the first, and so far only, motherboard available based on the nForce 980a SLI. Nvidia insists other partners are working with the chipset, but none are apparently ready to announce products just yet. That leaves the Socket AM3 SLI market all to Asus for now, which makes the M4N82’s sub-$170 asking price a pleasant surprise.

Perhaps the M4N82’s relatively affordable price tag can be explained by the board’s support for DDR2 memory rather than the DDR3 commonly associated with Socket AM3. That’s not necessarily a bad thing considering current memory prices; the cost of DDR3 has dropped quite a bit in the last six months or so, but DDR2 is cheaper still. For what it’s worth, Nvidia does say it has a reference design for the 980a that uses DDR3 memory.

Cosmetically, the M4N82 looks nearly identical to the M4A79T. The layout looks to be similarly excellent, as well.

I can’t let a motherboard review pass without mentioning power plug placement, a personal pet peeve of mine. Like its 790FX-based sibling, the nForce board’s auxiliary 12V connector is located along its top edge, right where we like to see it. This position ensures clean cable routing not only with traditional enclosures that put the PSU above the mobo, but also with upside-down cases that route power cables behind the motherboard tray.

The M4N82’s socket area looks to be about as clean as the M4A79T’s, but it’s not quite as accommodating. Our Ninja cooler proved a tight fit around the VRM heatsink, which flexed back slightly when the cooler was installed. You may also run into DIMM clearance issues with taller modules, although we didn’t with our Corsair Dominator sticks.

If you’ve been counting power phases, you’ll notice that the M4N82 has one fewer than the M4A79T. Both boards feed the CPU core with eight phases, but the M4A79T pipes an additional two phases to the processor’s north bridge component, while the M4N82 only dedicates one phase to that part of the chip.

A low-profile south bridge cooler leaves plenty of clearance for longer graphics cards. Gargantuan GeForces won’t interfere with the M4N82’s edge-mounted ATA or SATA ports, either. However, the fifth SATA port may be blocked by longer cards installed in the board’s third PCIe slot.

That’s somewhat more of an inconvenience considering that the third slot is where one would install the secondary graphics card in a two-way SLI setup. The blue PCIe x16 slots get a full 16 lanes of bandwidth each, while the black slot in between them is limited to eight lanes.

Like the M4A79T, the nForce board throws in a couple of standard PCI slots. Instead of a fourth PCI Express x16 slot, though, you’ll have to make do with an x1.

Wait, haven’t we seen this port cluster before? The M4N82’s collection of ports neatly matches that of the M4A79T. The only real difference here is the chip behind the Gigabit Ethernet port. Rather than farming out networking to a Realtek controller, the nForce board uses the GigE MAC integrated in the 980a MCP.

Busting into the BIOS

Asus can usually be relied upon to load a BIOS up with more than enough tweaking and overclocking options, and the M4A79T and M4N82 are perfect examples of why. The boards have nearly identical BIOS layouts and options, as if Asus has a block of code it cuts and pastes into the BIOS of every new mobo.

Asus M4A79T Deluxe Asus M4N82 Deluxe
Clock speeds Base: 200-600MHz in 1MHz
increments
DRAM: 800,1066,1333,1600MHz

PCIe:
100-150MHz in 1MHz increments
CPU/NB
:
800-3600MHz in 200MHz increments

HT: 200-2600MHz in
200MHz increments

Base: 200-600MHz in 1MHz
increments
DRAM: 667,800,1066MHz

PCIe:
100-200MHz in 1MHz increments
CPU/NB:
800-3600MHz in 200MHz increments

HT: 200-2600MHz in
200MHz increments

Multipliers CPU: 8X-35X in 0.5X increments CPU: 8X-35X in 0.5X increments
Voltages CPU: 0.8-1.7V in 0.0125V increments

CPU NB: 0.8-1.55V in 0.0125V increments

CPU VDDA: 2.5-2.8V in 0.1V increments

DRAM: 1.5-2.5V in
0.02V increments

HT: 1.2-1.5V in
0.02V increments
NB
:
1.1-1.4V in 0.02V increments
NB 1.8
:
1.8-2.0V in 0.2V increments
SB: 1.2-1.35V in 0.15V increments

CPU: 0.8-1.75V in 0.0125V increments

CPU NB: 0.8-1.55V in 0.0125V increments

CPU VDDA: 2.5-2.8V in 0.1V increments

DRAM: 1.8-2.5V in
0.02V increments

HT: 1.2-1.5V in
0.02V increments
NB: 1.1-1.4V in 0.02V increments
nForce 200: 1.2-1.5V in 0.01V increments

Monitoring Voltage, fan status, and
temperature
Voltage, fan status, and
temperature
Fan speed control CPU, system CPU, system

Prospective Phenom II overclockers are best off turning up the multiplier on an unlocked Black Edition processor. However, these boards also offer plenty of control over base clock speeds for those whose CPUs have locked upper multipliers. It’s possible to adjust the CPU north bridge, HyperTransport, and PCI Express clocks, as well.

Overclockers will also want to pay attention to the voltage options available on each board. The M4N82 offers a slightly higher CPU voltage ceiling, but the M4A79T’s 1.7V is more than enough juice to get you into trouble. Otherwise, the boards’ voltage ranges are nearly identical. You can even key in voltages manually rather than having to select them from a long list. This convenient capability also makes its way into the BIOS’s base and PCIe clock controls.

The M4N82 has built-in multipliers to take DDR2 memory up to 1066MHz, while the M4A79T is equipped to bring DDR3 all the way up to 1600MHz. Both BIOSes are loaded with timing options, including command rate controls.

Asus does a pretty good job with overclocking and memory tweaking options, but it could stand to pay more attention to automatic fan speed controls. The BIOSes allow users to choose between silent, optimal, and performance fan speed profiles for the CPU and system fan headers. The CPU fan can also be switched between three- and four-pin modes. However, there’s no way to define fan voltages manually or to target CPU or system temperatures.

Although having eight configuration profiles available in the BIOS is probably overkill, it’s nice that Asus provides support for different configurations. You’ll want to save a stable config at stock speeds before dabbling in overclocking or more extensive tweaking.

Specifics on specifications

As usual, we’ve consolidated vital motherboard specifications in a handy chart. There isn’t much to see here that we haven’t already discussed.

Asus M4A79T Deluxe Asus M4N82 Deluxe
CPU support Socket AM3-based
Athlon, Phenom processors
Socket AM2/3-based
Athlon, Phenom processors
Chipset AMD 790FX/SB750 Nvidia nForce 980a SLI/nForce 200
Interconnect PCI Express 2.0 (2GB/s) NA
Expansion slots 4 PCI Express x16

2 32-bit/33MHz PCI

3 PCI Express x16

1 PCI Express x1
2 32-bit/33MHz PCI

Memory 4
240-pin DIMM sockets

Maximum of 8GB of DDR3-800/1066/133/1600 SDRAM

4
240-pin DIMM sockets

Maximum of 16GB of DDR2-667/800/1066 SDRAM

Storage I/O Floppy disk

1 channel ATA/133

5 channels 300MB/s Serial ATA with RAID 0, 1, 0+1, 5 support

Floppy disk

1 channel ATA/133

5 channels 300MB/s Serial ATA with RAID 0, 1, 10, 5 support

Audio 8-channel HD audio via Realtek
ALC1200 codec
8-channel HD audio via Realtek
ALC1200 codec
Ports 1 PS/2 keyboard
1 PS/2 mouse

1 eSATA
6
USB
2.0 with headers for 6 more

1 RJ45 10/100/1000
via Realtek RTL8112

1 1394a Firewire via
VIA VT6315N with header for 1 more


1 analog front out

1 analog bass/center out
1 analog
rear out
1 analog surround out

1 analog line in

1 analog mic in

1 digital S/PDIF out (TOS-Link)

1 digital S/PDIF out (coaxial)

1 PS/2 keyboard
1 PS/2 mouse

1 eSATA
6
USB
2.0 with headers for 6 more

1 RJ45 10/100/1000
via Realtek RTL8211CL

1 1394a Firewire via
VIA VT6315N with header for 1 more


1 analog front out

1 analog bass/center out
1 analog
rear out
1 analog surround out

1 analog line in

1 analog mic in

1 digital S/PDIF out (TOS-Link)

1 digital S/PDIF out (coaxial)

Graphics for the platforms

For some folks, the choice between the 790FX and nForce 980a SLI will come down to the battle between CrossFire and SLI. We’ll take a closer look at graphics performance scaling with each in a moment. First, however, we should introduce the graphics cards we’ll be using today.

Asus’ ENGTX260 Matrix will be handling SLI duties. As one might expect, this card is based on the latest revision of Nvidia’s GeForce GTX 260. It comes with a 576MHz core clock, 1.24GHz shaders, and 896MB of GDDR3 memory running at an effective 2GHz. The price? A hair under $200.

Although the Matrix card doesn’t deviate from Nvidia’s default clock speeds for the GTX 260, it does swap out the stock heatsink for a custom dual-slot design. The cooler features two fans: an 80 mm unit in the middle of the card and a 70 mm unit to its right. Warm air is exhausted through a PCI back plate vent, which should be more effective than circulating it around inside a case for system fans to expel.

Unfortunately, the ENGTX260 is quite loud. The card is nearly quiet at idle, but even sitting at the Windows desktop for a while is enough to cause fan speeds to ramp up to distractingly loud levels. Asus would have been better off sticking with the stock cooler here.

We’ve also pulled a Radeon from Asus’ stable. In this case, it’s the EAH4870 Dark Knight. Based on the Radeon HD 4870, the Dark Knight has a 750MHz core clock and 1GB of GDDR5 memory pushing data at an effective 3.6GHz. The card is a relative bargain, too, with a $175 street price that can be further reduced with a $20 mail-in rebate that may or may not actually translate into a check in the mail some months from now.

Asus also opts for a custom cooler on the Dark Knight, but it’s a different design than that of the Matrix. There’s only one fan on the Radeon cooler, and the heatsink is exposed rather than shrouded. Without a shroud, it’s unlikely that air will be as effectively directed towards the card’s expansion plate exhaust port. I can live with that, though, because the Dark Knight is significantly quieter than the Matrix. The Radeon doesn’t crank fan speeds unless you fire up a game, and even then, its single fan generates less noise than the Matrix.

The Matrix and Dark Knight both come with DVI-to-HDMI and DVI-to-VGA adapters, component video dongles, PCIe power adapters, and multi-GPU connectors. For a limited time, the Dark Knight also includes a copy of Alone in the Dark, a game whose dismal Metacritic score fails to inspire much excitement.

Our testing methods

We ran each chipset through our full suite of tests with the ENGTX260 before swapping graphics cards for a more targeted look at gaming and multi-GPU performance. As AMD recommends, the 790FX was tested with the south bridge running in IDE rather than AHCI mode. We’ve also taken a closer look at the 790FX’s performance with different AHCI configurations. Nvidia’s nForce chipsets haven’t had such problems running in AHCI mode, which is how we configured the 980a.

All tests were run three times, and their results were averaged.

Processor

AMD Phenom II X4 955 3.2GHz
CPU/chipset link 2.0GHz HyperTransport

Motherboard


Asus M4A79T Deluxe


Asus M4N82 Deluxe
Bios revision 1103 0501

North bridge
AMD 790FX Nvidia nForce 980a
SLI/nForce 200

South bridge
AMD SB750
Chipset drivers Catalyst 9.5 ForceWare 15.26
Memory size 2GB (2 DIMMs) 2GB (2 DIMMs)

Memory type


Corsair CM3X1024-1333C9DHX DDR3 SDRAM
at 1333MHz


Corsair CM2X1024-9136C5D DDR2 SDRAM
at 1066MHz
CAS latency
(CL)
9 5
RAS to CAS
delay (tRCD)
9 5
RAS precharge
(tRP)
9 5
Cycle time
(tRAS)
24 18
Command rate 2T 2T

Audio codec
ALC1200
with 2.4 drivers
ALC1200
with 2.4 drivers
Graphics

Nvidia GeForce GTX 260 896MB
with ForceWare 185.85 drivers
Hard drive
Western Raptor X 150GB
OS

Windows Vista Ultimate x86
with Service Pack 1

Thanks to Corsair for providing us with memory for our testing.

Also, we’d like to thank Western Digital for sending Raptor WD1500ADFD hard drives for our test rigs.

We used the following versions of our test applications:

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

All the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Memory performance

We’re running different memory types at different clock speeds with different timings, so it’s no surprise to see the nForce and 790FX offer slightly different memory performance. The nForce fares better in the latency test, but the 790FX achieves higher bandwidth. Those results make some sense given that our DDR3 memory is running at higher clock speeds, while the DDR2 is configured with tighter timings.

STARS Euler3d computational fluid dynamics

Few folks run fluid dynamics simulations on their desktops, but we’ve found this multi-threaded test to be particularly demanding of memory subsystems, making it a good link between our memory and application performance tests.

Euler3D appears to prefer higher bandwidth over lower latencies, allowing the 790FX edge out the nForce here.

WorldBench

WorldBench uses scripting to step through a series of tasks in common Windows applications. It then produces an overall score. WorldBench also spits out individual results for its component application tests, allowing us to compare performance in each. We’ll look at the overall score, and then we’ll show individual application results alongside the results from some of our own application tests.

The 980a has two points on the 790FX overall. Let’s break out the individual application test results to see where the AMD chipset stumbled.

Although scores are tight through most of WorldBench’s multimedia editing and encoding tests, the nForce is a little quicker than the 790FX in the Photoshop test.

The nForce is faster in tests that include Firefox, as well. That’s no surprise considering that WorldBench’s Firefox tests have long favored systems with lower memory access latencies.

AMD regains some ground in the WinZip test, where the 790FX is faster than the 980a by more than 20 seconds. The nForce is a little quicker in the Nero test, though.

Gaming

This first wave of gaming tests uses relatively low resolutions and high in-game detail levels.

Although the 790FX comes out ahead in three of the four games, the frame rates are simply too close to call. Perhaps a higher resolution or in-game detail level will tease out more meaningful differences between these two platforms.

Multi-GPU scaling

In this next round of gaming tests, we’ve cranked the resolution to 1920×1200, turned on 4X antialiasing and 16X anisotropic filtering where possible, and maximized all in-game detail levels. Bring on the eye candy!

To see how AMD and Nvidia’s respective multi-GPU schemes scale, we’ve tested the 980a with a GeForce GTX 260 in single-card and SLI configurations, and the 790FX with a Radeon HD 4870 all on its own and in CrossFire. The GeForce and Radeon are evenly matched, for the most part, but we’re not looking at absolute frame rates here. Instead, pay attention to how much of a performance jump you can expect going from a single card to CrossFire or SLI.

While testing, I also decided to throw in a few cross-platform tests to see whether the GeForce or Radeon fared better when paired with their parent company’s chipset.

First, let’s talk multi-GPU scaling. Neither platform sees a performance jump with Far Cry 2‘s built-in benchmark. However, we do get decent scaling in the other three games. CrossFire and SLI increase performance by about 1.3 times in Quake Wars. In Call of Duty, the multi-GPU schemes nearly double frame rates.

Left 4 Dead is an interesting case, because CrossFire appears to scale much better than SLI. However, both hit the same performance wall at about 98 frames per second. Given that a single GeForce is faster than a lone Radeon by a good 20 FPS, I suspect the SLI config is being bottlenecked by our system’s processor.

Looking at the performance of our cross-platform configurations, there doesn’t appear to be a clear advantage to pairing a Radeon with the 790FX or a GeForce with the nForce. Not while you’re running a single graphics card, anyway.

Serial ATA performance

The Serial ATA disk controller is one of the most important components of a modern core logic chipset, so we threw each platform a selection of I/O-intensive storage tests using a Western Digital VelociRaptor.

IOMeter

We’ll begin our storage tests with IOMeter, which subjects our systems to increasing multi-user loads. We used IOMeter’s workstation and database test patterns, since those are more appropriate for desktop systems than the file or web server test patterns.

From the SB600 through the most recent SB750, AMD’s south bridge chips have all used essentially the same storage component. The SATA controller is a Silicon Image design, and from the beginning, it’s had inconsistent performance in AHCI mode, a mode that enables access to some key SATA features like Native Command Queuing and hot-swapping. The SB750 will soon be replaced, but we thought it appropriate to explore the AHCI issue one more time to see what’s what with the latest drivers.

Below you’ll find results for the 790FX running in IDE mode with AMD’s Catalyst 9.5 IDE drivers. We’ve also tested the AMD chipset in AHCI mode using the generic Microsoft AHCI driver that Vista automatically installs. AMD has its own AHCI drivers, too, and we’ve tested their latest 3.1.1540.127 revision.

When paired with Vista’s AHCI driver, the 790FX manages to keep up with the nForce 980a SLI. Running the AMD chipset in IDE mode results in significantly lower transaction rates, likely due to this mode’s lack of support for NCQ. What’s even more interesting is the performance of AMD’s own ACHI driver. It’s no quicker than IDE mode up to 32 outstanding I/O requests, and after that, it’s actually slower.

In the past, we’ve only seen decent AHCI performance from AMD south bridge chips combined with unreasonably high CPU utilization. That isn’t the case here, though. The Vista AHCI driver does consume more CPU cycles than the nForce, but we’re only talking about a couple of percentage points.

Today’s lesson: AMD’s AHCI drivers are still broken. Horribly, horribly broken.

HD Tach

We used HD Tach 3.01’s 8MB zone test to measure basic SATA throughput and latency.

The 790FX is back in IDE mode for HD Tach, and that may be why it stumbles in the sustained write speed test. However, we’ve seen inconsistent performance from the SB750 in the write speed test before, particularly when running in AHCI mode with Vista’s drivers.

There’s no difference in random access times between the 790FX and 980a.

Although overall CPU utilization is high in HD Tach, the AMD and Nvidia chipsets are evenly matched.

USB performance

Our USB transfer speed tests were conducted with a USB 2.0/Firewire external hard drive enclosure connected to a 7,200-RPM Seagate Barracuda 7200.7 hard drive. We tested with HD Tach 3.01’s 8MB zone setting.

USB performance has never been a strong suit of AMD chipsets, and the 790FX doesn’t change that. The nForce delivers much higher transfer rates, although they do come along with higher CPU utilization.

Ethernet performance

The nForce 980a’s integrated Gigabit Ethernet controller is every bit as competent as the Realtek chip used by Asus’ 790FX board.

PCI Express performance

We used ntttcp to test PCI Express Ethernet throughput using a Marvell 88E8052-based PCI Express x1 Gigabit Ethernet card.

For some reason, the nForce’s PCIe GigE throughput is a good 140Mbps slower than that of the 790FX. The CPU utilization of the two is comparable, though.

PCI performance

To test PCI performance, we used the same ntttcp test methods and a PCI VIA Velocity GigE NIC.

The nForce’s PCI GigE throughput is a little faster than the AMD chipset’s.

Power consumption

We measured system power consumption, sans monitor and speakers, at the wall outlet using a Watts Up Pro power meter. Power consumption was measured at idle and under a load consisting of a multi-threaded Cinebench 10 render running in parallel with the “rthdribl” high dynamic range lighting demo. Results that fall under “No power management” were obtained with Windows Vista running in high-performance mode, while those with power management enabled were taken with Vista in its balanced performance mode.

It’s often difficult to make much of power consumption differences between chipsets because we’re invariably dealing with different motherboards. However, the M4A79T and M4N82 are nearly identical, which makes the 790FX’s lower power consumption particularly notable. Only 10W separates the two boards at idle, but under load, the nForce pulls 30 more watts.

I suspect some of the nForce’s higher power consumption can be traced to its integrated graphics component, which may draw juice even though it’s unused by the Asus board. However, that doesn’t explain the 30W difference in load power consumption.

Overclocking

Phenom II overclocking is best done with a Black Edition processor with an unlocked upper multiplier. In fact, Black Edition CPUs are just about the only AMD processors we’d currently recommend. But do either of these boards have an advantage when turning up the multiplier on a Phenom II X4 955?

No. Both allowed our Black Edition to run stable with a four-way Prime95 load at 3.7GHz.

3.7GHz on the M4A79T…

And on the M4N82

The boards hit 3.6GHz with the stock CPU voltage. 3.7GHz proved a little more demanding, requiring a 1.5V core voltage in each BIOS. On the M4A79T, setting 1.5V in the BIOS resulted in 1.5V being detected by CPU-Z. With the same core voltage setting in its BIOS, the M4N82 registers 1.456V in CPU-Z. I wouldn’t make too much of the difference; CPU-Z doesn’t always read CPU voltages reliably.

Overclocking success is never guaranteed, of course, but both these boards look well-suited to pushing a Black Edition Phenom II to its limits.

Motherboard peripheral performance

Core logic chipsets integrate a wealth of peripherals, but they don’t handle everything. Firewire and audio are farmed out to auxiliary chips, for example. To provide a closer look at the peripheral performance you can expect from the motherboards we’ve tested today, we’ve complied Firewire and audio performance results below. We’ve used motherboard rather than chipset names here, because these performance characteristics reflect the auxiliary peripheral chips used on each board rather than the performance of the core logic chipset.

HD Tach
Firewire performance

Read burst

speed (MB/s)


Average read

speed (MB/s)


Average write

speed (MB/s)


CPU utilization

(%)


Asus MA79T Deluxe
39.4 33.3 25.5 7.7

Asus Mn82 Deluxe
38.6 33.2 21.6 8.7

With the same Firewire chip, it’s no surprise that the Asus boards are evenly matched in our Firewire tests.

RightMark Audio
Analyzer audio quality

Overall score

Frequency response

Noise level

Dynamic range

THD

THD + Noise

IMD + Noise

Stereo Crosstalk

IMD at 10kHz

Asus MA79T Deluxe
4 5 4 4 5 3 4 5 4

Asus M4N82 Deluxe
5 4 4 5 3 4 5 4 4

The two boards use the same Realtek audio codec, too, but the M4N82’s overall score in RightMark Audio Analyzer is a little higher than the M4A79T’s. The 790FX board does score better in some of RMAA’s individual tests, though.

Conclusions

The stripped-down nature of Asus’ M4A79T and M4N82 Deluxe motherboards is perfect for a chipset comparison because the core logic components can step to the forefront without being overshadowed by the excesses that overrun most high-end mobos. I like the idea of building enthusiast-oriented boards that stick to the basics, and Asus nailed all the important stuff. These Deluxe fraternal twins both have fantastic layouts virtually free of clearance conflicts and niggling quirks. They’re sparsely but sensibly equipped. And as you’d expect from Asus, there are more BIOS tweaking and overclocking options on hand to put even a savvy enthusiast in over their head.

There are one or two small problems with this formula, however. A single Gigabit Ethernet controller hardly screams Deluxe to me, especially when many other boards in the $165-190 price range come with a pair of GigE jacks. If not a second Gigabit connector, then put on some kind of secondary networking option, preferrably Wi-Fi. I’m also disappointed with the ALC1200 audio codec. Asus would be much better off using the ALC889A, whose real-time Dolby Digital Live encoding capabilities make the ALC1200’s higher model number look a little silly.

Otherwise, these are solid boards with very similar application performance. Which one is better depends on your preferences and priorities.

The M4A79T Deluxe costs $25 more than the nForce board without really offering more of anything. At least the SB750’s AHCI mode seems to get along with Vista’s generic storage controller drivers. The M4A79T also has much lower power consumption than its nForce 980a-based counterpart, especially under load, where the gap is a whopping 30W. However, the M4A79T has a few problems, including relatively poor USB performance and CrossFire’s history of supporting new games more slowly than SLI.

A lower price tag may leave the M4N82 Deluxe with less to prove, but as the only nForce 980a SLI on the market, this board is also the poster child for Nvidia’s finest Socket AM3 chipset. It’s telling, then, that Asus has completely ignored the chipset’s integrated graphics processor. On a high-end motherboard primed for multi-GPU configurations, there’s simply no need for an IGP. There really isn’t a need for DDR3, either. DDR2 remains less expensive, and at least with the Phenom II, making the switch to DDR3 won’t greatly improve application performance.

The M4N82 certainly has its share of baggage, particularly its relatively high power consumption. The lower throughput we observed with a PCIe-based Gigabit Ethernet card is also disappointing. However, the nForce 980a board does appear to be the more robust platform when it comes to multi-GPU configurations. Years of experience testing graphics cards tells us that SLI typically offers better performance with newer games. AMD usually takes longer to optimize CrossFire for new releases.

In the end, choosing between the 790FX and nForce 980a SLI should come down to which multi-GPU scheme you prefer. There’s simply no need to opt for a high-end chipset with this many PCIe lanes unless you intend on running multiple graphics cards—aAnd in games, those graphics cards will influence performance far more than the chipset or motherboard. As a result, I’m inclined to favor the nForce 980a SLI and the M4N82 Deluxe over the 790FX and M4A79T in what is ultimately a very close contest. A contest so close, in fact, that both boards are TR Recommended.

Comments closed
    • sparkman
    • 10 years ago

    Is it true? Are the SB750 SATA/AHCI problems fixed in the Vista drivers? I wish the article addressed that question more directly.

    > In the past, we’ve only seen decent AHCI performance
    > from AMD south bridge chips combined with
    > unreasonably high CPU utilization. That isn’t the case
    > here, though.

    To me, looking at the graphs, SB750 is performing well with Vista. Just don’t install AMD’s own SATA/AHCI drivers.

      • Kurotetsu
      • 10 years ago

      Huh, so it was never a hardware issue. AMD’s southbridge drivers just suck.

        • vikramsbox
        • 10 years ago

        Beats me why they can’t get out good drivers for a SATA protocol taht’s been out for more than 3 years now. I can’t imagine generic drivers being better than the company ones!

          • Meadows
          • 10 years ago

          I can easily imagine Microsoft knowing their mojo a lot better than AMD, though.

    • crazybus
    • 10 years ago

    I should note that on the spec sheet you have the M4A79T Deluxe listed as being compatible with AM2 processors, which it is not.

    Also, minor nitpick, but I don’t think the M4N82 should really be referred to as an AM3 board, since it’s DDR2 and all. Aren’t those boards AM2+?

    AMD’s relatively poor peripheral performance is disappointing. I wonder if there’s some issue with your external HDD enclosure and the SB750’s USB controller. 15/MB/sec doesn’t really cut it.

    • jughead79
    • 10 years ago

    I think you’re mistaken in your calculations of Crossfire vs. SLI scaling in Call of Duty. The Crossfire set-up is scaling over 2X which is more than the SLI set-up.

      • Dissonance
      • 10 years ago

      Looks like some other results got mixed up in the formula. Fixed.

    • gerryg
    • 10 years ago

    Nice review. I’d love to see a Micro-ATX comparo, too.

    • loophole
    • 10 years ago

    I think you’ve got the memory types and timings swapped around for the two boards on page 6, as the M4A79T is the DDR3 board but it’s listed as using the DDR2 memory while the M4N82 is listed as using the DDR3 memory.

    No big deal as it’s easy enough to figure out what’s really going on, but I figured I should point it out anyway.

    Other than that, nice article Geoff!

    EDIT: Excellent – fixed now.

    • pluscard
    • 10 years ago

    I just built a server based on socket AM3. I used the triple core 720, 8gb of ddr3 1300, a pair of raptors in raid1 for the system/program, and a pair of g.skill falcons in raid1 for the data drives.

    The whole project cost under $1400, not counting $6k for the microsoft licenses. Since the license is per cpu, I wanted as many cores/performance as I could get. My upgrade option is to drop in a 955, and get a bit more ghz, as well as one more core.

    The majority of server boards are all still ddr2/667 or /800, which no longer is impressive today. I opted to use a desktop board instead because of the memory i/o speed.

    I’d like to have more than 8gb of ram, but still waiting on the larger 4gb sticks, which are due anytime.

      • flip-mode
      • 10 years ago

      $relevance = 0;

        • pluscard
        • 10 years ago

        Ok – the board has a 790GX – it’s the jetway from the AM3 previous review.

        Relevant enough?

        Btw, most people have a “genuine need” when the build a new pc.

          • flip-mode
          • 10 years ago

          When I say “genuine need”, I mean “OMG my computer just quit working”, not “OMG my computer is a Pentium 3”. I’d say most people on this site upgrade because they want something faster, not because their existing stuff plain stopped working. If your current stuff is still functional, it is, IMO, totally foolish to jump on AM3 right now with Lynnfield and P55 being just a couple of months away. It is very likely that combo will be as attractive or more attractive than an x4-955 / 790FX.

            • SomeOtherGeek
            • 10 years ago

            I agree… I will/have to wait. We have 2 slow machines right now, but they are still functional. Of course, at times, the family gets impatient with them and ask for the faster PCs. No, 4 PCs in a household of 4 is not enough! Spoiled, I know.

            I want to wait more cuz I wanna see what Lynnfield has to offer. I still want an i7 system anyway. I’m hoping that with all these choices that the i7 prices will drop and I’ll just get the 920, just cuz I want one to compare performance with the P45 systems. I have read everything, but there is nothing like hands-on experience. And I would like to have a AMD just for the heck of it too. But if the Lynnfield blows away the AMD, I’ll go that direction even if it costs more. So many damn decisions.

            I like to have systems that are last awhile. So, AMD might be out of the picture just cuz of that. Not to swap with it, if another Intel breaks down. Man, I don’t know. Got a million bucks so that I can just buy everything?

    • flip-mode
    • 10 years ago

    Nice review Geoff. Interesting vid cards.

    Lack of Dual Gig-E would be a big omission for me to swallow; in fact, right now I am posting from a virtual machine that is using a bridged eth card and I really don’t have enough slots in my mobo to dedicate an eth card to as many virtual machines as I plan on running. And also, while I like high end boards, I also like integrated graphics.

    What about AMD’s Overdrive – does that factor into the value proposition at all?

    With Lynnfield just around the corner, buying right now would have to be due to a genuine /need/.

    Last point – the x4-955 is a hard sell with the Q9550 selling for $230. Yeah, 775 is dead, but the future is far from certain – is there really going to be something from AMD worth upgrading to from an X4-955? Something that would compel me to spend some green just to have the pleasure of having an x4-955 sitting in my desk drawer? I wouldn’t swap out a CPU just for a few percentage points, or even necessarily more cores. If I was that type of consumer, I’d have already replaced my current CPU.

    • MadManOriginal
    • 10 years ago

    One thing I don’t quite agree with is that no integrated graphics on an otherwise higher-end mobo is a waste. While I understand what you’re saying there are very valid uses, some people have uses for lots of CPU power but don’t need much more than basic graphics so a good mobo with integrated graphics would be perfect for them.

      • Dissonance
      • 10 years ago

      There are plenty of good integrated graphics motherboards that aren’t saddled with the price premium attached to chipsets with this many PCIe lanes.

        • SomeOtherGeek
        • 10 years ago

        Yea, I just wonder why? Why now? (So many PCIe lanes) Should we be expecting something? It is quite a change especially on the AMD chipset side. Will more and more people be going the XFire/SLI route?

        What do you think?

        I know, I’m stereotyping, but I always think AMD as integrated graphics and nForce/Intel as non-integrated graphics… I don’t know why? I guess I have been drooling over the higher-end more than I should…?

        But yes, I’m looking at the AMD MB more and more now cuz of the price drops and such cheap high end boards. It is pretty amazing what a person can buy now.

          • swaaye
          • 10 years ago

          I more amazed with what can be had for $75-85.

          As for multiGPU becoming “mainstream”, I don’t see that ever happening. Few games these days, in our brave new console-driven world, even benefit in a really tangible way from a single “high end” GPU. Also can’t ignore the other catches to multiGPU including huge power usage, heat, and potential for driver problems and/or games that can only use one GPU. Inefficiency-R-Us.

          I’m actually much more into the microatx mobos now. Currently I don’t even use more than one or two expansion slots in any of my systems at home or at work. The days are long gone when you had to add a NIC, sound card, dedicated 3D card, some I/O card, etc and used lots of slots. The fullsize boards just look ridiculously wasteful in their big ‘ol mid/full tower cases. Best left for servers now IMO.

            • SomeOtherGeek
            • 10 years ago

            I totally agree with you! 100%!

            I bought a ASUS P5Q Deluxe thinking I’ll go XFire or SLI. Boom! Shot myself in the foot. What a waste of 200 bucks!

            I’m thinking like you now. MicroATX all the way. A board with 2 RAM slots and dedicated graphics with a 16x PCIe for future. AMD really looks hot in that department… Thinking like you, 80 bucks for a MB, 40 bucks for RAM and 100 bucks for CPU and wow! Wife will be happy. 220 bucks for the core system totally blows me away!

            • MadManOriginal
            • 10 years ago

            I was looking at that route recently. I quickly realized however that for anything more than the most basic gaming at low resolution any IGP will not cut it. Even cheap (now) 2 year used cards blow away IGPs. It’s great to have for basic use or for an add-in upgrade in the future but if you use an IGP you won’t be doing little real 3D gaming.

            • mattthemuppet
            • 10 years ago

            I don’t know, even with a 740G MB (equivalent to a 2400XT? something like that) I can still play most games fine. Some at the expense of quality settings, though i never play a game just because it /[

            • MadManOriginal
            • 10 years ago

            Yeah there are just lots of qualifications is all – resolution, quality settings, AA/AF etc. I guess overall what I’m saying is that an IGP, while nice and may provide an acceptable experience in certain games, is still blown away by a discrete GPU that can be had pretty cheap. But whatever works for the individual is what matters!

            I recently downgraded from a GTX 260-216 to a 9600GT (part of my ‘sell it while it has value’ upgrade cycle. although I see no reason to jump on a better card asap.) So far it’s played games I play fine even with settings turned up a bit although it’s a little boarderline even on older titles like HL2 at 1920×1600. The 9600GT cost me $45 which granted was a pretty good used forum deal price, but for not much (~$25) more I had lots of choices.

            btw I’ve been running an e8400 on a DFI LP P45 Jr since December so I’m with you on the mATX angle. The only thing that bugs me a little about some IGP mATX boards atm is the slot choice and layout. Do we really still need 2 PCI slots? I imagine by the time I’m ready to get a new stup, probably around late 2010 with 32nm Intel CPUs and whatever AMD has at the time PCI may be down to one slot or totally dead.

            • SomeOtherGeek
            • 10 years ago

            That is why I said a MicroATX with a 16X PCIe slot and then you are all set. You can get what we stated and then add a graphics card later if/when there is a demand for it. But for most everyday use, it is perfect! Takes no room, boots fast and runs 90% of the apps smoothly. For kids and web/email users, it is perfect. Is that why AMD is around so long…? They know their customer base?

            The performance difference of a $80 to a $200 board is not a whole lot. It is all the flash and eye candy that people won’t even see unless there is a window on the case. Kinda defeats the purpose.

            • pluscard
            • 10 years ago

            If I’m not mistaken, you can also crossfire the pci-e gpu with the IGP to get even more performance – if you ever get to that level.

            • swaaye
            • 10 years ago

            There are limits to that that make it a waste of money unfortunately.

            For example, 780G will only CF with like a HD3450. The GF8x00 will only SLI with a GF8500. Very gimpy. Will get you very little speed improvement. Much better off buying a sub $100 card that’ll completely blow that combo away.

            Even more disappointing is that the Hybrid Power stuff that is supposed to shut down the discrete card in favor of the IGP is apparently very finnicky. Read that right here in a TR comment post a while back.

            • swaaye
            • 10 years ago

            I’d actually argue that the performance difference between is zilch outside of the inability to do dual GPU.

            If you’re building a system that isn’t going to run two video cards, there’s just no real reason not to go microATX. You get a lot more for your money.

            • MadManOriginal
            • 10 years ago

            I agree with you, AMD has had the advantage in IGP chipsets over Intel for a while now for what I’d call pretty light gaming. Personally I don’t trust NV chipsets but the 9000 series chipsets do well in games too. There is a difference in $80-200 cards though, it just depends upon other factors like I said in the other reply and the difference per dollar grows a lot when looking at used cards. It’s all about what suits the intended use and the user.

        • MadManOriginal
        • 10 years ago

        Fair enough but that’s a little different from what you said in the article. There are a few uses for numerous PCIe slots although it gets pretty esoteric once you’re above a 16x slot and a few 1x slots.

    • Mr Bill
    • 10 years ago

    You recently reviewed the MSI 790FX-GD70 which is going for ~$170 on line right now. It should have been in this lineup. Maybe you had to send it back to the vendor? I bought that board and the AMD 955 Black Edition. I have 8GB as 4 x 2GB sticks of OCZ Platinum DDR3 2000 PC3(16000) running at DDR3 1600 at 1.61V in XP-64 and its a sweet system. Have not even tried overclocking the CPU but the memory subsystem is pretty good to handle 4 sticks at DDR3 1600.

      • bimmerlovere39
      • 10 years ago

      I think the comparison here was more focused on comparing two different chipsets on motherboards that were as similar as possible, hence both being Asus boards.

        • Mr Bill
        • 10 years ago

        Well, not to put too fine a point on it but the title is “High-end Socket AM3 chipsets under the microscope”. In the previous review the MSI board was dismissed for being ‘too high end and expensive’. Also, the memory in that roundup seems to bench a bit slow or maybe its Vista but when I run the SisSoft memory bandwidth test I don’t get 11.6x GB/sec. I am seeing 13.5X GB/sec when I run 4x2GB sticks at 800MHz and 1:4 FSB:DRAM = DDR3 1600 at 8,8,8 24, 32, 2T.

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