Nvidia’s nForce 750a SLI chipset

Nvidia’s flagship nForce 780a SLI chipset for Socket AM2+ processors debuted a couple of months ago, bringing all-new silicon loaded with a Phenom-ready HyperTransport 3 link, integrated graphics with HD video decoding and HybridPower capabilities, and support for three-way SLI. While it’s a technical marvel, this high-end chipset didn’t really make sense to me—it’s too much like wrapping the guts of a Ferrari around the engine from a Golf GTI. There’s nothing wrong with the Golf, of course, but you’re only working with so much horsepower, which makes the Ferrari bits overkill. What you need for a high-end exotic is an engine with a little more grunt.

If you’re building a chipset for Socket AM2+ processors, there’s only so much grunt available. The Phenom just can’t keep up with Intel’s fastest Core 2 Quads, forcing AMD to price itself out of the high end of the processor market. The most expensive CPU AMD currently makes is the Phenom X4 9950 Black Edition, which, at just $235, costs nearly as much as the cheapest nForce 780a SLI motherboards on the market. Hardly a match made in heaven.

What you really want to pair with a Phenom is a mid-range motherboard around the $150 mark. Something like XFX’s $149.99 MD-A72P-7509, perhaps. This board is based on the 780a’s little brother, the nForce 750a SLI, and the two are very much alike. Keep reading to see how the 750a stacks up against not only its big brother, but also AMD’s 790FX chipset in a battle for Socket AM2+ supremacy.

All but an nForce 780a

Those not already familiar with the nForce 780a SLI would do well to read our initial coverage of the chipset. The 750a is very similar, and it doesn’t bring any new features and capabilities. Mostly, it just takes some away.

The nForce 780a SLI is a two-chip, er, chipset made up of an nForce 780a SLI MCP that contains all the basic core-logic functionality and an nForce 200 SLI chip loaded with PCI Express lanes. The 750a ditches the nForce 200 completely, and despite a change in name, its MCP component is essentially identical to that of the 780a. This 65nm chip hosts not only core logic elements, but also an integrated graphics core very similar to what you’ll find in the GeForce 8300.

Dubbed a motherboard GPU (mGPU), this graphics core is fully DirectX 10-compliant with 16 stream processors and support for Shader Model 4.0. More importantly, it’s capable of full Blu-ray decode acceleration across AVC, VC-1, and MPEG2 formats, with HDMI output thrown in for good measure. HD video decoding is a neat trick, but it’s not nearly impressive as the mGPU’s HybridPower implementation. HybridPower allows the mGPU to take over for compatible discrete graphics cards at idle, completely shutting them down for substantial power savings.

The energy efficiency proposition for HybridPower becomes even more compelling with SLI configurations, where watts saved are multiplied. However, without an nForce 200 SLI chip riding shotgun, the 750a is limited to only 19 lanes of PCI Express 2.0 connectivity—not nearly enough for three-way SLI. 16 of those lanes are reserved for graphics and can be split evenly between a pair of cards for two-way SLI. Thanks to the higher signaling rate of PCI Express’ second coming, this dual-x8 link provides just as much bandwidth as a dual-x16 link with gen-one PCIe.

Of course, Nvidia has long been adamant that the nForce 200 is more than just a collection of PCI Express lanes. The chip includes broadcast and posted-write shortcut functions that can reduce the bandwidth used by SLI configurations. One might expect these functions to be absent in the 750a, but Nvidia tells us they’ve been built right into the MCP. We’ll see how the 750a’s SLI performance compares with that of the 780a a little later in this review.

In addition to differences on the SLI front, the only 780a feature missing from the nForce 750a is support for Enhanced Performance Profile (EPP) memory. Yes, you’ll have to set memory timings manually, just like in the olden days when we walked to school through knee-deep snow, up-hill both ways. EPP memory is certainly a welcome convenience, but I’d wager that many mid-range buyers would balk at paying the premium associated with EPP DIMMs, anyway.

AMD 790FX Nvidia nForce 780a SLI Nvidia nForce 750a SLI
Processor interface 16-bit/2GHz HyperTransport 16-bit/2GHz HyperTransport
16-bit/2GHz HyperTransport

PCI Express 2.0 lanes
38 35
19

Multi-GPU support
CrossFire 2, 3-way SLI
2-way SLI

Chipset interconnect
PCIe 1.1 x4 PCIe 2.0 x16
NA
Interconnect bandwidth 2GB/s 16GB/s
NA
Serial ATA ports 4 6
6
AHCI Y Y
Y
Native Command Queuing Y Y
Y
RAID 0/1 Y Y
Y
RAID 0+1/10 Y Y
Y
RAID 5 N Y
Y
ATA channels 2 1
1
Max audio channels 8 8
8
Audio standard AC’97/HDA HDA
HDA
Ethernet N 10/100/1000
10/100/1000
USB ports 10 12
12

Since they’re based on the same MCP chip, the nForce 750a has the same Phenom-ready HyperTransport 3 link as its high-end brethren, the same six 300MB/s Serial ATA RAID ports (that work in AHCI mode, I might add), the same dozen USB ports, and the same Gigabit Ethernet controller. Reusing MCP chips in different products to hit a range of price points makes good business sense for Nvidia. This approach also pays dividends for enthusiasts, who benefit from high-end features trickling down to more affordable parts.

Before moving on, I should note that you won’t find a chipset interconnect or interconnect bandwidth listed in the table above because the 750a is a single-chip solution, with need for a chip-to-chip interconnect. It’s an elegant approach that eliminates a potential bottleneck.

XFX’s MD-A72P-7509 motherboard
The 750a in its element

Manufacturer XFX
Model MD-A72P-7509
Price (Street)
Availability July

Our first look at the nForce 750a SLI comes courtesy of XFX’s MD-A72P-7509 motherboard. This board’s goal seems to be channeling 750a’s inherent goodness rather than wowing users with indulgent excess. XFX doesn’t even resort to catching your eye with flashy board colors—classic PCB green is back, baby. After the veritable rainbow of multicolored mobos that have paraded through the Benchmarking Sweatshop over the years, the retro look is a welcome change. However, unless you’re running a case window, a motherboard’s aesthetic appeal lasts only minutes before it’s effectively shuttered from the world inside an enclosure that is ideally never to be opened again. So much for style.

XFX pulls most of the board’s functionality from the chipset, so we don’t find much in the way of auxiliary ports, slots, and peripheral chips. This approach gives the board designers plenty of square footage to work with, resulting in a clean layout with few clearance problems.

We tend to be particularly picky about the placement of power plugs, and XFX does well to put the auxiliary 12V connection up along the top edge of the board where cabling won’t interfere with airflow around the CPU socket. If you run an upside-down case like CoolerMaster’s Cosmos 1000, though, you’ll probably need an extension cable to reach the 12V plug. XFX keeps the primary power connector mid-way down the board, so cable reach shouldn’t be a problem there.

Power is routed to the CPU socket through four-phase circuitry that betrays the MD-A72P-7509’s modest aspirations. The board is only rated for use with processors that have a thermal design power (TDP) up to 95W, leaving the Phenom X4 9850 and 9950 Black Edition CPUs that carry respective 125W and 140W TDPs off of the official compatibility list. XFX says the cost of supporting those power-hungry chips was too high, and that upcoming AMD processors won’t have TDPs that exceed 95W.

AMD may eventually settle on a processor lineup with a 95W ceiling, but they’re not there yet, and the easy-overclocking Black Editions are currently the most attractive Phenoms on the market for enthusiasts. We can, however, report that our board didn’t seem to have any problems running a 9850 through our standard chipset test suite—at least on an open test bench. Your mileage may vary.

Like many recent motherboards, XFX’s take on the 750a covers the voltage regulation circuitry with a beefy heatsink linked to the chipset cooler. Some have questioned whether connecting chipset and VRM cooling is a wise idea, since there’s the potential for heat from the latter to creep down to the former. But the board’s chipset is also sitting in a major hot spot—between two graphics slots with little room for airflow—so it’s probably a good idea to have heat piped up to cooling fins that should sit right in front of a chassis exhaust port.

XFX’s chipset cooler is a low-profile affair, and it probably needs the heat pipe. The short fins do keep the heatsink out of the way of longer graphics cards, though. Unfortunately, longer double-wide cards installed in the green PCIe x16 slot (which also happens to be the primary graphics slot), will block access to three of the board’s SATA ports. Had XFX moved the ports just a little further down the board, this wouldn’t be an issue.

Next to the Serial ATA ports is a two-digit POST code display that’s extremely useful when troubleshooting. XFX throws in onboard power, reset, and CMOS clear buttons, too. We’re pleased to see CMOS reset buttons becoming more common, although we’d ideally like them in a more accessible location in the port cluster.

Jumper blocks make an appearance in the slot stack, where XFX kicks it old-school with a manual SLI switch that controls PCIe lane routing. Switching from single-card to SLI mode involves popping four large jumper blocks, which really isn’t a big deal since it’s something you’ll probably only have to do once. It would have been nice if XFX included a jumper pulling tool to make it easier to perform this bit of surgery while the board is still installed in a case, though.

In total, the board packs three PCI slots, a pair of PCI Express x1 slots, and two PCIe x16 slots for graphics. The top x16 slot isn’t functional when running the board in single-card mode. However, the 750a’s Hybrid SLI support allows compatible graphics cards to be used in conjunction with the mGPU to power additional displays.

Just to the left of the top PCIe x16 slot in the picture above, you can just make out a Marvell networking chip. For whatever reason, XFX chose to tap an auxiliary Gigabit Ethernet chip with the MD-A72P-7509 rather than using the GigE MAC integrated in nForce 750a chipset.

Just about everything one might expect makes an appearance in the port cluster, including a choice of DVI and HDMI video outputs. You get external Serial ATA connectivity, too, but not Firewire. The lack of Firewire probably won’t be a deal-breaker for many, but it is a disappointing omission on a $150 motherboard.

On the audio front, the board serves up two flavors of digital S/PDIF output backed by Realtek’s ALC888 codec chip. This chip doesn’t support on-the-fly Dolby Digital Live or DTS encoding, limiting multichannel digital output to sources with pre-encoded audio tracks, such as movies. If you want multichannel output in games, you’ll need to switch to the board’s analog audio outputs.

While not technically a part of the port cluster, an internal Serial ATA port is tucked just behind the VGA port. This isn’t an extra port so much as a conduit through which the port cluster’s eSATA port is fed. To get the eSATA port to work, you have to string a Serial ATA cable up from one of the board’s SATA ports to the one behind the port cluster.

The BIOS, times two

While most motherboards make do with a single BIOS chip, the MD-A72P-7509 features two. The second chip is essentially meant to be a backup, and it can be accessed by simply flipping an onboard jumper. Both chips are socketed, as well, so they should be easy to replace or swap should one succumb to corruption during a flash attempt.

Of course, failed flashes are relatively rare, at least among enthusiasts. It’s what’s inside the BIOS that really counts, and here XFX comes up a little short.


Bus speeds
CPU base clock:
100-500MHz in
1MHz increments

PCIe: 100-200MHz in 1MHz increments

DRAM: 200, 266, 333, 400, 533MHz
SB-K8: 200-2600MHz in 200MHz
increments
mGPU core: 500-1023MHz in 1MHz increments
mGPU shader:
1500-2500MHz in 1MHz increments


Bus multipliers
NA (Phenom X4 9850 BE)
Voltages CPU:
1.0-1.45V in 0.05V increments
CPU NB:
1.0-1.45V in 0.05V increments

DRAM: +0.05-0.35V in 0.05V increments

Chipset: +0.03-0.09V in 0.03V increments


Monitoring
Voltage, fan
status, and temperature monitoring

Fan speed control
CPU

Most of the board’s overclocking and tweaking options are consolidated under an appropriately-named JUSTw00t! menu option. XFX, it seems, is not without a sense of humor.

The JUSTw00t! interface starts off well enough, with all the memory timings you’d expect and an adequate range of voltage and bus speed options. CPU voltages scale up to 1.45V in 0.05V increments, and you can push the memory voltage up to 0.35V above stock. The BIOS also provides control over the processor north bridge voltage and the amount of juice supplied to the chipset. There isn’t nearly as much granularity in the voltage options as we’ve seem with some boards, but unless you’re really into fine-tuning, that shouldn’t be a major problem.

On the bus speed front, CPU reference clock options are available between 100 and 500MHz in 1MHz increments. One can also tweak the PCI Express, DRAM, and HyperTransport link speeds, in addition to fiddling with the motherboard GPU’s core and shader clocks.

That all sounds great, but there’s one key component missing: control over the Phenom multiplier. Multiplier manipulation works just fine with an Athlon X2, but when running AMD’s latest quad-core chips, the only control one has over the processor multiplier is a cryptic set of “P-State” options that don’t seem to work. Of course, Phenom X4 9850 and 9950 Black Edition processors with unlocked upper multipliers aren’t officially supported by the board, and I suppose that blunts the need for multiplier control.

XFX’s BIOS finds redemption with temperature-based fan speed control, giving users the ability to set a target CPU temperature, tolerance, and even the start-up fan speed. We only wish these controls were extended to the board’s system fan headers rather than being restricted to the processor fan.

For those who are a little skittish about poking around in a motherboard BIOS, Nvidia’s system utility software brings a measure of overclocking and tweaking functionality to Windows. This app does rely on motherboard makers to implement BIOS hooks for certain features, though, and XFX has some work to do on that front.

The latest version of Nvidia’s system utility supports individual multiplier control for each of a Phenom’s four cores. This capability was previously restricted to AMD’s OverDrive software, which only worked with the company’s own chipsets. Unfortunately, the options don’t range beyond our Phenom’s default multiplier of 12.5, which sort of misses the point.

In addition to restricted multiplier control, the Nvidia system utility lets users play with various bus speeds, including the CPU base clock. XFX hasn’t made voltage and fan speed controls available to the app, though.

Support for the system utility’s voltage and temperature monitoring capabilities is also missing from the XFX board. This certainly isn’t the first time we’ve seen a motherboard fail to take full advantage of Nvidia’s Windows tuning and overclocking software, and that’s really a shame; the system utility is one of the best applications of its kind, and it’s available free of charge from Nvidia’s website.

Specifics on specifications

As ever, we’ve whipped up a handy quick-reference specifications chart for your viewing pleasure.


CPU support
Socket AM2/AM2+ Phenom,
Athlon X2 processors

North bridge
Nvidia nForce 750a SLI
MCP

South bridge

Interconnect
PCI Express 2.0 (16MB/s)

Expansion slots
2 PCI Express x16

2 PCI Express x1
3 32-bit/33MHz PCI


Memory
4 240-pin DIMM
sockets

Maximum of 8GB of DDR2-533/667/800/1067 SDRAM


Storage I/O
Floppy disk

1 channel ATA/133

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

Audio 8-channel HD audio via Realtek
ALC888 codec
Ports 1 PS/2 keyboard
1 PS/2 mouse

4 USB
2.0 with headers for 6 more

1 RJ45 10/100/1000 via Marvell 88E8056

1 eSATA (shared with onboard SATA ports)
1 DVI out
1 VGA out
1 HDMI out

1 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 TOS-Link S/PDIF out
1 digital coaxial S/PDIF
out

There isn’t much to see here, but do take note that the board only offers a total of 10 USB ports. The nForce 750a SLI chipset actually has a dozen ports available, but XFX apparently lost a couple in translation.

Our testing methods

We’re pitting the nForce 750a SLI against not only its big brother, but also AMD’s 790FX chipset. The 790FX may actually be the 750a’s closest competitor, with our MSI K9A2 Platinum available with the same $150 street price as the XFX MD-A72P-7509.

We’ve had numerous problems getting the 790FX chipset’s SB600 south bridge component working correctly in AHCI mode. Not only do you need an auxiliary storage controller (or a slipstreamed SP1 disc) to install Vista, but we’ve found that you also have to choose between drivers that offer strong performance with poor CPU utilization or those that exhibit low CPU utilization with weak performance. Given these issues, you’re better off running the SB600 in native IDE mode, which we did for our testing. The nForce chipsets have no problem running in AHCI mode, which is what we used for those platforms.

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

Processor

Phenom X4 9850 Black Edition
System bus 2GHz HyperTransport

Motherboard


MSI K9A2 Platinum


Asus M3N-HT Deluxe


XFX MD-A72P-7509
Bios revision 1.3 T0425A 1.0

North bridge
AMD 790FX Nvidia nForce 200 Nvidia nForce 750a SLI
MCP

South bridge
AMD SB600 Nvidia nForce 780a SLI
MCP
Chipset drivers Catalyst 8.4 ForceWare 18.11 ForceWare 18.11
Memory size 2GB (2 DIMMs 2GB (2 DIMMs) 2GB (2 DIMMs)

Memory type


Corsair CM2X2048-8500C5 DDR2 SDRAM
at 714MHz
CAS latency
(CL)
4 4 4
RAS to CAS
delay (tRCD)
4 4 4
RAS precharge
(tRP)
4 4 4
Cycle time
(tRAS)
12 12 12
Command rate 2T 2T 2T

Audio codec
ALC888
with 1.91 drivers
AD1988B with 6.10.1.6320
drivers
ALC888
with 1.91 drivers
Graphics

GeForce 8800 GT 1GB PCIe
with ForceWare 169.25 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.

All of our test systems were powered by OCZ GameXStream 700W power supply units. Thanks to OCZ for providing these units for our use in testing.

Finally, 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

The 750a gets off to a good start in our memory subsystem tests, but then all three of these chipsets share the same integrated Phenom memory controller. Any differences here can be chalked up to how each motherboard maker has chosen to tune the processor’s on-die memory controller, and it looks like XFX has slightly favored bandwidth over latency.

Motherboards don’t always handle four DIMMs gracefully, so we popped an additional two memory modules into each system for another round of tests.

Adding DIMMs doesn’t change the picture much. The 750a’s memory bandwidth is even greater here, and its access latency exactly matches that of the nForce 780a.

The following latency graphs are a little indulgent, so I won’t be offended if you skip them. They show access latencies across multiple block and step sizes, painting a fuller picture of memory controller performance with each chipset. Yellow represents L1 cache, light orange is L2, red is L3, and dark orange is main memory.

As one might expect from systems that share the same on-die Phenom memory controller, the access latency picture looks pretty similar from one chipset to the next.

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.

The 750a can’t quite catch the 790FX in our fluid dynamics simulation test, but it’s close.

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.

We nearly have a three-way tie in WorldBench, with only one point separating the contenders. The 750a sits in second place here, just behind its high-end nForce counterpart.

Focusing on WorldBench’s multimedia editing and encoding tests, the 750a lags a little behind the 780a. The scores are very close together, though.

The results in WorldBench’s office and multitasking tests are tight, as well, with the 750a scoring a first, second, and third place finish.

The 750a remains closely matched with the 790FX in our 3ds max tests. It looks like the 780a built much of its overall lead in the modeling test, which depends on integrated graphics performance.

While Nero is too close to call, the 750a is a full 27 seconds slower than the 780a in the WinZip test. That still puts it neck and neck with the AMD’s 790FX, though.

Gaming

The 750a doesn’t get much opportunity to stretch its legs through our first wave of game tests. No more than a few frames per second separate the fastest system from the slowest across four recent titles.

SLI performance

We were curious to see whether the nForce 750a’s dual-x8 SLI implementation could keep up with the dual-x16 goodness available in the 780a, so we hooked up a pair of GeForce 9800 GTX graphics cards in SLI for a little additional testing on the nForce boards. For these tests, we cranked all in-game detail levels and ran with 4X antialiasing and 16X aniso (with the exception of Crysis, of course). We also updated our graphics drivers to the latest ForceWare 175.19 release and pushed the display resolution as high as our monitor would accommodate in each game.

Across the board, the nForce 750a delivers slightly lower framerates than its nForce sibling. That’s a pretty good result considering that the 750a is effectively working with half the graphics slot bandwidth. Today’s games don’t seem to mind being restricted to a dual-x8 SLI configuration, at least when those lanes are second-generation PCI Express.

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 Raptor WD1500ADFD.

IOMeter

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

The 790FX’s long-standing problems running in AHCI mode are a handicap here, allowing the nForce chipsets to deliver higher transaction rates that scale more aggressively as we move from a single outstanding I/O request up to 256 concurrent requests. Here, the 750a is every bit as fast as the 780a.

IOMeter response times look a little closer, but again, it’s the nForce chipsets delivering more responsive performance. As one might expect from chipsets that share the same MCP component, the 750a and 780a are essentially tied.

Despite performing more transactions per second, the nForce chipsets don’t consume more CPU cycles than the 790FX in IOMeter.

HD Tach

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

The 750a and 780a remain closely matched through HD Tach’s transfer rate tests. Note how both have a huge lead over the 790FX in sustained write speeds. We’ve found that this test takes advantage of storage controllers that support Native Command Queuing to enable substantially higher transfer rates.

Access times are too close to call.

The results of HD Tach’s CPU utilization test are within the app’s +/- 2% margin of error for this test.

USB performance

Our USB transfer speed tests were conducted with a USB 2.0/Firewire external hard drive enclosure connected to a 7200RPM Seagate Barracuda 7200.7 hard drive. We tested with HD Tach 3.01’s 8MB zone setting.

Nvidia’s nForce chipsets have long had an edge over the competition when it comes to USB performance, and that hasn’t changed with the 750a, which is quite a bit faster than the 790FX. However, the 750a’s write speeds can’t quite match those of the 780a. The 750a also consumes a few more CPU cycles than its kin, although when you factor in HD Tach’s +/- 2% margin for error in the CPU utilization test, the results are close.

PCI Express performance

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

At least with our Gigabit Ethernet card, PCI Express performance is a wash.

PCI performance

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

PCI performance is close, too, although it’s worth noting that the nForce boards have slightly higher throughput than the 790FX.

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.

Nvidia’s chipsets have long consumed more power than their competition, but the 750a is an improvement. Dropping the nForce 200 SLI chip has definitely helped, allowing our XFX board to consume nearly as few watts at idle as the notoriously frugal 790FX. However, the picture changes under load, where the 750a actually pulls more juice than the 780a. Don’t make too much of the load results, though; we are running a 125W Black Edition Phenom that exceeds the 750a board’s maximum processor TDP. I suspect the power circuitry is a little overloaded here and probably not at its most efficient.

Overclocking

Without working Phenom multiplier control in the BIOS, we were forced to take our overclocking testing to Windows. That’s not an entirely bad place to be thanks to Nvidia’s system utility software. With the system utility, we were able to drop the multiplier on each core to 5X to take processor limitations out of the equation. We also set a memory bus limit of 400MHz, relaxed our memory timings, and dropped the HT processor link speed before turning our attention to the CPU base clock.

The MD-A72P-7509 cruised up to a 230MHz CPU/HyperTransport base clock without issue, although our top speed required a chipset voltage boost of 0.03V to remain stable under a four-way Prime95 load. 240MHz crashed the system no matter how much additional chipset or processor voltage was applied.

A 30MHz overclock doesn’t look all that impressive, but we haven’t had much luck pushing Phenom clock speeds. Anyone keen to overclock a Phenom processor is better off taking advantage of the unlocked upper multiplier on Black Edition CPUs rather than fiddling with the CPU base clock.

Motherboard peripheral performance

Core logic chipsets integrate a wealth of peripherals, but they don’t handle everything. To provide a closer look at the peripheral performance you can expect from the motherboards we’ve tested today, we’ve complied Ethernet and audio performance results below.

NTttcp Ethernet

performance
Throughput (Mbps)
CPU utilization (%)

Asus M3N-HT Deluxe
934 8.5

MSI K9A2 Platinum
933 23.1

XFX MD-A72P-7509
932 8.3

We normally include Ethernet results in our collection of chipset performance graphs, but since the XFX board we tested taps an auxiliary Marvell chip, networking performance really isn’t influenced by the chipset. That said, the Marvell chip performs admirably, and it looks to be every bit as fast as the nForce 780a’s integrated GigE MAC.

RightMark Audio
Analyzer audio quality

Overall score

Frequency response

Noise level

Dynamic range

THD

THD + Noise

IMD + Noise

Stereo Crosstalk

IMD at 10kHz

Asus M3N-HT Deluxe
4 5 3 3 3 1 3 5 3

MSI K9A2 Platinum
4 5 3 3 3 1 3 4 3

XFX MD-A72P-7509
4 5 3 3 3 1 3 4 3

Analog audio output quality, at least according to RightMark Audio Analyzer, is very close between all three motherboards. Only the Asus manages to separate itself, and then by only one point in the stereo crosstalk test.

Conclusions

The nForce 750a SLI chipset is essentially a 780a with fewer PCI Express lanes and no support for SLI threesomes. But while 780a boards will set you back at least $230, 750a offerings like the XFX MD-A72P-7509 can be had for just $150. That’s an $80 savings, which, for a Phenom line that tops out in the mid range, is quite substantial. Buyers in this price bracket aren’t likely to mind the 750a’s lack of three-way SLI support, and given the performance of its dual-x8 SLI implementation, they probably won’t miss the extra PCIe lanes, either.

With its motherboard GPU, the nForce 750a is easily the most interesting mid-range chipset for Socket AM2+ processors. You essentially get GeForce 8300-class integrated graphics for free, complete with HD video decode acceleration for Blu-ray movies. And when paired with a compatible graphics card, the 750a’s HybridPower capability can deliver substantial idle power savings.

Even if you discount its mGPU, the 750a still has a solid feature set. The MCP delivers plenty of Serial ATA RAID ports with working AHCI support—something that continues to be a struggle for AMD’s 790FX. Throw in a dozen USB ports, an integrated Gigabit Ethernet controller, and apparently reasonable power consumption, and the 750a looks formidable indeed.

That brings us to XFX’s MD-A72P-7509 motherboard, which fails to take full advantage of the 750a in several ways. First, it leaves two USB ports on the table at a time when USB peripherals are more popular than ever. The board also shuns the 750a’s integrated GigE MAC—perhaps in an attempt to distance itself from the sub-prime mortgage crisis—in favor of an auxiliary Ethernet controller from Marvell. Nvidia may not have the best reputation for reliable networking, but we haven’t had any problems with the company’s integrated Gigabit Ethernet controllers since ActiveArmor acceleration was dropped. We don’t have a problem with the Marvell chip, either, but it does consume a PCI Express lane, and that’s a precious commodity on the 750a.

By far the biggest problem with XFX’s take on the 750a has nothing to do with the chipset, though. The board’s 95W processor TDP ceiling excludes the most attractive Phenoms in AMD’s lineup—Black Edition models with unlocked upper multipliers. That won’t be a problem if you’re looking to plug in an Athlon X2, of course, but it’s a serious limitation for those looking to build a quad-core rig. What this board really needs is for AMD to release a 95W Black Edition Phenom with an unlocked upper multiplier.

I don’t want to get too down on the MD-A72P-7509; it’s a solid board that offers competitive performance and an impressive feature set. At the moment, though, we can only recommend it to those looking to build an SLI rig around an Athlon X2 processor. Enthusiasts craving Phenom’s four cores should look elsewhere, as there are several 750a-based boards that don’t share the XFX’s 95W processor limitation.

Comments closed
    • tommyboy812
    • 11 years ago

    Can someone tell me where (or if) I need to plug in the sound output for a sony IDE DVD/CD Drive on this motherboard… The Sony drive indicated that these may be unnecessary aif the mobo can handle digital audio input… (sorry I’m dazed an confused after staying up till 1AM trying to find wher it plus in…) Thanks for any help!

    • mattthemuppet
    • 11 years ago

    nice review. Just one point – given that every MB review I’ve read here for some time has the same comment under the HD Tach CPU utilisation graph (low, within +/- 2% margin of error), is there any point still including it?

      • Usacomp2k3
      • 11 years ago

      There are always new readers…

    • PBCrunch
    • 11 years ago

    Can the DVI and HDMI ports both be used at the same time (to connect a pair of DVI displays)?

      • Dissonance
      • 11 years ago

      No. The chipset is limited to a single digital output.

    • henfactor
    • 11 years ago

    Great review!
    I have the GIGABYTE GA-M750SLI-DS4 and it’s a great board. Overclocks great (AM2 4200+ 2.9Ghz), and hybridpower works well with my 9800GTX.
    And I don’t think my board has the 95 watt limit.

      • shank15217
      • 11 years ago

      Not everybody overclocks and nvidia chipset has way better i/o performance.

        • asdsa
        • 11 years ago

        …and way higher power consumption.

        • Kent_dieGo
        • 11 years ago

        Even if not overclocked you would have to assume it will be more reliable as it would have much higher overclocking headroom.

          • swaaye
          • 11 years ago

          Nah. Both companies do extensive testing to assure stability of their hardware. Overclocking potential is not related to their guarantee of stability at the default settings. An overclocker doesn’t even have access to the types of tests that are done to validate hardware and I highly doubt that most overclockers create tweaked systems with the same stability as the stock settings provide.

          Consider server boards. You don’t judge one of those by how well it can overclock.

    • Kent_dieGo
    • 11 years ago

    How can they call this a socket AM2+ motherboard if it cannot support all socket AM2+ chips? Not being able to handel 140W chips is scary if you plan to do any overclocking.

    • Prototyped
    • 11 years ago

    Good review as usual. I was a bit disappointed to see its integrated USB performance suffer a bit compared to the 780a, but nevertheless, for the price, it’s pretty damn good. It’s a better value than the 780a and (IMO) the AMD 780G at any rate.

    I would have liked to see a comparison of the IGPs on the nForce 780a and AMD 780G, though, as well as video decode performance. I suspect mATX versions of these boards have a chance at becoming popular for HTPC builds.

    Now where’s that 750*[

    • MadManOriginal
    • 11 years ago

    When you overclock doesn’t that make the TDP limitations moot anyway?

    • phez
    • 11 years ago

    Such a beautiful board.

      • DrDillyBar
      • 11 years ago

      good layout.

    • Steel
    • 11 years ago

    q[

      • Dissonance
      • 11 years ago

      The jumper block switches digital video output between DVI and HDMI.

    • crabjokeman
    • 11 years ago

    It would be interesting to see a 780G/SB7x0 tested too.

    • Usacomp2k3
    • 11 years ago

    Looks like a nice board. Integrated graphics too. $300 for a nice board+cpu+ram. I like.

    • Tarx
    • 11 years ago

    The high power consumption at load on this MB was noted as “I suspect the power circuitry is a little overloaded here and probably not at its most efficient.”
    Can this be verified with a lower powered CPU?
    And yes, I wish AMD would come out with 95W 9650BE.

    • flip-mode
    • 11 years ago

    No firewire on the rear port cluster, an unfortunate omission.

    It’s really sad to see AMD’s chipset be so considerably overwhelmed in all forms of I/O.

    It’s very nice to see IGP functionality on higher end boards.

    • excession
    • 11 years ago

    Sounds like a decent board.

    A question, Geoff, about the review – as we know, PCIe 2.0 8x should have the same bandwidth as PCIe 1.1 16x. You state this in the early part of the review. However, you attempt to explain away SLI performance differences as being due to reduced bandwidth on the 750a. Can you explain? ๐Ÿ™‚

    Also, typo on the first line of the last page.

    Cheers!

    James

      • Meadows
      • 11 years ago

      There are no PCIe 1.1 lanes tested in this review.

      • KarateBob
      • 11 years ago

      The 780a in SLI mode two 16x slots with 16 lanes of PCIe2.0 (8GT/s for each slot)
      The 750a in SLI mode only has 8x lanes of PCIe 2.0 (4GT/s each slot)

    • pedro
    • 11 years ago

    More boards please that aren’t choked down with piles and piles of stuff I’ll never use. There’s something elegant about a board with ample room everywhere.

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