SLI for the masses arrives (sorta)
If you’ve followed our coverage of nVidia’s scaleable link interface (SLI), you know that we’ve been anxiously waiting for an SLI-capable mobo that doesn’t require registered memory or an expensive workstation CPU. (SLI, of course, is nVidia’s solution for running two PCI-E videocards in tandem for extra 3D rendering oomph.)
Well, our wait is over, because the nForce4 chipset in the ASUS A8N-SLI Deluxe lets you run an Athlon 64 FX-55 CPU, regular DDR memory, and not one but two GeForce 6800 Ultra cards (as well as any other nVidia videocards that support SLI). Unlike some monstrous hardware kludge projects that yield very little performance for extra effort and money, the A8N-SLI/ 6800 Ultra combo delivers the goods—ultra-high-res gaming with AA turned on. You can, for example, comfortably play Half Life 2 at 100 fps per second with 4x AA and 8x anisotropic filtering at 1600x1200.
The board features two x16 PCI Express physical slots, two x1 PCI-E slots, and three 32-bit PCI slots. Even with the board packed with two GeForce 6800 Ultra cards, you still have two slots free.
Located between the two long x6 PCI-E slots is the nForce4’s magic ingredient—a PCI Express lane configuration board. When the board is set in single-card mode, the main PCI-E slot runs in x16 mode, while the second long PCI-E slot runs at x1. Reverse the board, and the two slots go into SLI mode, each running at x8. Nvidia says it’s found that the best performance comes from running both videocards balanced at x8.
The mobo is ATX 12V 2.0 complaint, which means it uses the new 24-pin power connector. For running the ASUS off an older 20-pin power supply, ASUS provides a feature called EZ-Plug, which lets you plug a standard four-pin peripheral power connector into the motherboard next to the PCI-E slots. ASUS says this will let the board operate with older 20-pin PSUs when two videocards are installed. It sounds good on paper, but we found EZ Plug to be a little unreliable with our test motherboard. For PSU duties, we used a PC Power and Cooling 510 Deluxe Express, and even with both videocards plugged directly into the power supply and the 24-pin connector in place, the BIOS prompted us to plug a power cable into the EZ-Plug.
The A8N-SLI gives you a smorgasbord of storage options. Between onboard chipset support for four SATA 3Gb/s drives (which support a unique form of RAID that can combine PATA and SATA drives) and a separate Silicon Image 3114 controller with four SATA ports, you’d be hard pressed to places to plug in your storage options. We also like the inclusion of two PATA ports, as a lot of newer PCI-E boards are cutting back to only one. There are simply too many legacy devices in use today for any mobo manufacturer to assume just one PATA port is enough.
Contrary to what we originally thought, the nForce4 chipset will not support Intel’s HD Audio. For this reason, the ASUS board taps a 16-bit RealTek part for sound chores. Of course, 99.99 percent of all geeks will ditch the integrated sound for higher quality audio (we did all of our testing with an Audigy 2 ZS Gamer card).
In the benchmark hoedown, the A8N-SLI and its FX-55 lil’ buddy busted a mighty respectable jig. To wit: We’ve seen a 3.6GHz Xeon system running SLI'ed 6800 Ultras pull down 3DMark 2005 scores in the 7,300 range. We put the same two cards into the A8N-SLI and hit 9,475 without any serious tweaking. And some vendors have told us that they’ve cracked the 10,000 barrier with the A8N-SLI and 6800 Ultra cards already.
We also saw excellent memory bandwidth numbers using SiSoft Sandra: The A8N-SLI was able the break the 6,000MB/s barrier. In comparison, a 3.46GHz P4EE system running DDR2 topped out at 5,780MB/s, while a VIA K8T800 Pro board running an Athlon FX-55 and regular DDR got winded at 5,780MB/s.
The A8N-SLI isn’t a perfect motherboard. We’re still a little bewildered by the configuration of the EZ-Plu, and the arms for the RAM modules are too close to the videocards for comfort. Still, we give ASUS points for shipping the first PCI-Express Athlon 64 FX mobo—and it supports SLI to boot! --Gordon Mah Ung
+ nForce: Pluses: PCI Express and SLI arrive for the Athlon 64 FX!
- nFarce: RAM slots too close to video card can scrap components off your video card.