PCI Express SLi Info Review
Motherboards Video Cards nVidia ATI?
The new PCI Express interface, a properly
equipped computer can use two graphics cards in tandem. It's not the first
time we've seen this sort of thing; old schoolers may recall stringing
together a pair of 3dfx Voodoo 2 cards back in the Windows 95 days. It is,
however, the first time we've been able to pair two modern graphics cards.
We haven't yet seen a complete, working dual 3D card setup in action (word
is stability issues plagued the early parts supply), but it won't be long
before twin 3D cards become as commonplace in high-performance PCs as
laser-cut cases and liquid cooling.
nVidia provides the only way to run
two PCIe graphics cards in the same system, with its scalable link
interface, a.k.a. SLI. If you do remember the aforementioned 3dfx dual 3D
card scheme, also called SLI (in that case, scan line interleave)
you'll appreciate nVidia's nod to the past. The new incarnation is currently
available in prebuilt systems from PC vendors such as GEN-X-PC, Alienware, Falcon
Northwest, and Velocity Micro. SLI joins two matching nVidia-based
6000-series graphics cards--in most cases, by way of a motherboard using
nVidia's AMD-only Nforce-4 SLI chipset and a pair of PCIe x16 slots. nVidia
also designed each of its SLI-compatible PCIe graphics cards with a row of
pins along the top edge that can accept an nVidia SLI connector that joins
them.
An nVidia
SLI system includes a PCI Express motherboard that supports two physical
connectors that are capable of having two BFG PCI Express graphics cards
plugged into them. Joined by the nVidia SLI connector, the two graphics
cards power one monitor, delivering earth-shattering PC performance.
Screenshot courtesy of 3DMARK03.
IMPORTANT:
Graphics cards MUST be from the same manufacturer and contain identical GPUs.
For example, a BFG GeForce 6600 GT OC can only be paired with another
GeForce 6600 GT OC graphics card.
Your other option, of course, is to build
an SLI system yourself. nVidia has released SLI versions of some of its PCIe
cards, including the GeForce 6800 Ultra, the GeForce 6800 GT, the GeForce
6800, and the GeForce 6600 GT. You'll need two of these cards to start. Then
you'll need a motherboard that provides two x16 PCIe slots and the SLI
connector to link the two cards. Asus announced its A8N-SLI Deluxe
motherboard on November 17, 2004, and we expect it to show up in stores
soon. Micro Star International has told us that its K8N Neo4 Platinum/SLI
board will hit shelves at the end of December
According to nVidia's
Web site, you'll need two of the exact same cards in order to make
SLI work. And not just two cards using the same chip--they must also be from
the same nVidia retail partner. For example, you wouldn't be able to join a
Gainward GeForce 6800 GT with a PNY 6800 GT. The cards must both be of the
same make and model. Power concerns are important because you can be sure
that PCs running two GeForce 6800 Ultra cards will have monstrous power
demands and require some intense cooling. You'll want to be sure to consult
your motherboard manual before you purchase a power supply, especially
because we found no such guidelines on nVidia's Web site
While the
only option for a dual graphics card solution pins you to nVidia and AMD for
the moment, you can be sure that other players want in on the extreme 3D
action. Intel and nVidia recently signed a partnership that will allow
nForce chipsets to support Pentium CPUs, which means that Intel-based SLI
motherboards can't be too far behind. If you're wondering what ATI is doing
about all of this, you're not alone. We've asked, and the company isn't
saying much. We don't expect it to be quiet for too long, though. You might
also expect to see chipset makers such as Via make a foray into motherboards
with dual PCI Express x16 slots. If these chipset makers can meet the
standards of nVidia's SLI certification program, you may see those
motherboards include the SLI connector as the Nforce4-based motherboards.
