This month sees ATI matching the dual 16x chipset launched by NVIDIA a few months ago by feeding two CrossFire cards with as much bandwidth as they can handle.
ATI wants the Xpress 3200 to be the best performance chipset available, and has made it with overclocking in mind. The BIOS lets you adjust any speed, frequency or multiplier you want. ATI claims the silicon itself draws around a third of the power of its SLI rival and thus dissipates less heat, giving more headroom for pushing the various buses. This is a boon to ATI fans, as the board was slightly slower in our application benchmarks at stock speeds than the nForce4 X16 Asus A8N32-SLI Deluxe, 1.23 compared to 1.25. While this small difference isn’t noticeable in general use, it’s another feather in the nForce4 cap.
It’s the implementation of dual 16x PCI Express data channels that ATI really feels is the strength of the Xpress 3200 chip. SLI X16 routes one graphics connection from the north bridge and the other from the south bridge, which ATI claims leads to unnecessary arbitration, and thus lower performance. The Xpress 3200 north bridge chip hosts both data connections, which ATI believes is more efficient.
Asus pairs the Xpress 3200 with a ULi M1575 south bridge, which provides four SATA 2 connectors. While this has the NCQ and RAID0, 1, 5 and 0+1 capabilities of nForce4, we prefer the latter for its MediaShield technology that can alter live RAID arrays. A fifth SATA connector resides near the I/O ports; this being a throw-off from the Silicon Image 3132 chip that powers an external SATA 2 connection. While SATA 2 external hard disks are as yet rare, they offer up to 300MB/s transfer speeds compared to the 50MB/s of FireWire or 60MB/s of USB 2, which modern disks can saturate.
There’s no hardware firewall on this board as you’d find on an nForce4 equivalent. Two third-party chips provide the dual Gigabit Ethernet here. In compensation, the ULi chip can talk to High Definition Audio codecs rather than the ageing AC97 codecs of nForce4.
However, ATI will need to speed work on its forthcoming south bridge, the SB500, as NVIDIA has recently acquired ULi and board makers can’t rely on chips from this company to support Xpress 3200 for much longer. Judged purely on speed, features and value, the nForce4 Asus 8N32-SLI Deluxe wins on all counts: it’s faster in our benchmarks, extras such as the hardware firewall and MediaShield storage controller are handy, and it costs only about $20 more.
However, when buying a dual-slot motherboard, you have to consider which graphics cards you’re likely to use. And as we showed back in May (page 43), SLI wins over CrossFire for convenience and reliability. Despite the best efforts of Asus, the A8R32-MVP Deluxe doesn’t have the appeal of the A8N32-SLI Deluxe.
