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Athlon 64 chipset comparison

Four paths to PCI Express

WHILE SOME MAY say that AMD arrived late to the PCI Express party, one could argue that Intel showed up a little early. The truth probably lies somewhere in between. Compelling PCI-E graphics cards didn't make an appearance until well after Intel's 900-series chipset launch, but they materialized some time before PCI Express-equipped Athlon 64 motherboards were available on the open market. NVIDIA's nForce4 platform was the first PCI Express chipset to be widely available for the Athlon 64, but VIA's K8T890 and ATI's Radeon Xpress 200 weren't far behind. SiS recently joined the fray with the SiS756, and even ULi managed to work its way into the mix with its M1573 south bridge companion for ATI's Radeon Xpress 200 north bridge.

With at least four platforms to choose from, the Athlon 64's PCI Express chipset lineup finally has some depth. But between the latest core logic options from ATI and ULi, NVIDIA, SiS, and VIA, which chipset has the most desirable blend of features and best performance? Join us as we sift through spec sheets and pore over a slew of benchmark results to find out.

The specs
Today we'll be splitting our attention between the NVIDIA nForce4 Ultra, SiS SiS756, VIA K8T890, and ATI Radeon Xpress 200 paired with ULi's M1573. Let's kick things off with a look at how the chipsets' north bridge features compare.

ATI Radeon Xpress 200 NVIDIA nForce4 Ultra SiS SiS756 VIA K8T890
HyperTransport link 16-bit/1GHz 16-bit/1GHz 16-bit/1GHz 16-bit/1GHz
PCI Express lanes 22* 20 16 20
North/south bridge interconnect type 2 lanes PCI Express N/A (Single chip) MuTIOL Ultra V-Link
Peak theoretical interconnect bandwidth 1GB/s N/A (Single chip) 1.06GB/s 1.06GB/s

All of the north bridge chips support PCI Express, but some have more lanes than others. ATI's Radeon Xpress 200 north bridge technically has the most PCI Express lanes at its disposal, but it uses two of those lanes for its north-south bridge interconnect, so only 20 are available. The NVIDIA and VIA chipsets also have 20 PCI-E lanes to play with, allowing them to support x16 and x4 slots, or even hang peripherals directly off the north bridge. The SiS756 north bridge only supports enough PCI Express lanes to power an x16 slot, leaving support for extra PCI-E lanes and peripherals up to the south bridge.

ATI is so keen on PCI Express that they've used a pair of lanes for the Radeon Xpress 200's north/south bridge interconnect. SiS and VIA opt for proprietary interconnects, dubbed MuTIOL and Ultra V-Link, respectively, but all three offer about 1GB/sec of interconnect bandwidth. NVIDIA's nForce4 Ultra is the only one without a north/south bridge interconnect; as a single-chip design, it doesn't need one.

Although we won't be focusing on integrated graphics performance in this comparison, it should be noted that ATI's Radeon Xpress 200 also includes an integrated graphics controller. It's the only DirectX 9-class IGP available for the Athlon 64 platform, and thanks to ATI's SurroundView technology, the IGP can work in conjunction with ATI graphics cards to power additional displays.

With the Athlon 64's memory controller residing on the CPU, there isn't much else going on in the north bridge. However, the corresponding south bridge chips have plenty to offer, including each chipset's storage, networking, and audio controllers.

ULi M1573 NVIDIA nForce4 Ultra SiS SiS965 VIA VT8237R
PCI Express lanes 4* N/A (Single chip) 4 0
SATA ports 4 4 4 4*
SATA peak data rate 150MB/s 300MB/s 150MB/s 150MB/s
Native Command Queuing Y Y N N
ATA channels 2 2 2 2
ATA RAID support N Y N N
Max audio channels 8 8 8 8
Audio standard HD/AC'97 AC'97 AC'97 AC'97
Ethernet 10/100 10/100/1000 10/100/1000 10/100
USB ports 8 10 8 8

NVIDIA's single-chip nForce4 Ultra easily has the most feature-rich storage controller of the lot. It's the only chip to support 300MB/sec Serial ATA II transfer rates and ATA RAID, and its ability to span multiple RAID arrays across both Serial and "parallel" ATA drives is unique. The nForce4 Ultra also takes the cake when it comes to networking, where it serves up a hardware-accelerated Gigabit Ethernet MAC and integrated firewall. And don't forget USB, where the nForce4 Ultra offers two more ports than the competition. Although really, how many of us need more than eight USB ports? Audio is clearly the nForce4 Ultra's most glaring weakness, but few of its competitors do better than vanilla AC'97.

In fact, ULi's M1573 is the only Athlon 64-compatible south bridge to support Intel's "Azalia" High Definition Audio standard, which allows for sampling rates and resolutions up to 192kHz at 32 bits. However, like just about every other south bridge short of SoundStorm, the M1573 lacks hardware acceleration for 3D audio.

ULi bolsters the M1573's best-in-class audio controller with four Serial ATA ports that support RAID and Native Command Queuing. The chip also has a total of four PCI Express lanes, although two of those are consumed by the interconnect between it and the ATI Radeon Xpress 200 north bridge.

VIA's VT8237R is the most dated south bridge in the field. With the exception of a trailing R, the chip appears to be identical to the VT8237 that VIA has been pushing since the days of the KT600 Socket A chipset. In some cases, maturity is a good thing. Unfortunately, the VT8237's "proven technology" doesn't include PCI Express lanes or support for Native Command Queuing. We should also point out that although the chip supports up to four Serial ATA RAID ports, an external PHY is required to take advantage of two of them. To date, we've yet to see a production VT8237 implementation use more than two of the chip's SATA ports.

Unlike the weathered VT8237, the SiS965 is a new addition to the Athlon 64 south bridge sweepstakes. With a pair of PCI Express lanes and an integrated Gigabit Ethernet MAC, the chip comes pretty well-equipped, too. However, unlike NVIDIA, SiS makes no hardware acceleration claims for its Gigabit Ethernet controller. We'll see how its throughput and CPU utilization stack up in our Ethernet tests. The SiS965 also lacks support for Native Command Queuing, which is a little disappointing, but it does sport four SATA ports for storage, including RAID.