Quad SLI

We were shown several PCs which, of course, sport Quad SLI GeForce 7900 GTX cards. They were all complemented by Dell 30" LCD panels which support the Extreme High Definition resolution of 2560x1600. How we wish we could own those beauties...

Come, take a look at these pictures of the Dell XPS 600 Quad SLI PC and the new Quad SLI GeForce 7900 GTX cards!

The Dell XPS 600 PC	Quad SLI GeForce 7900 GTX

If you are wondering, no, there won't be any more Quad SLI GeForce 7800 GTX. That Quad SLI demo which featured two dual GPU GeForce 7800 GTX was a one-off demo. With the new cooler and faster GeForce 7900 GTX, there's really no point in selling Quad SLI GeForce 7800 GTX, right?

As you can see, the Quad SLI GeForce 7900 GTX actually consists of FOUR cards. Instead of two GPUs on the same card, NVIDIA combined two single GeForce 7900 GTX cards into a combo card with a single PCI-E connector. As such, each resulting card is a dual-slot solution.

The card is really long, but it uses a relatively small cooler. Curiously, although the card comes with vents on the backplate, the shroud on the cooler does not extend to the vents. So, the hot air doesn't really get exhausted out the back.

Because this is really a two-card combination, the lower card has its fan inlet cut into the card itself. If you take a close look at the picture of the back of the card, you can see the inlet holes for the lower card's fan.

Although cumbersome, this solution of using two-card combos to create Quad SLI seems to work just fine. We gave it a spin and it was darn responsive.

Here's a look at the Quad SLI's design logic. As we know, there are two GeForce 7900 GTX GPUs on each car, each with its own 512MB framebuffer. They are all directly connected to each other via SLI links. They are also connected to a special 3-way, 48-lane PCI Express bridge chip.

This bridge chip allows the card to communicate with a PCI-E 16X slot. For maximum performance, NVIDIA of course recommends that Quad SLI be installed on an NVIDIA nForce 4 SLI X16 motherboard which supports full 16X links on both PCI-E 16X

While it's quite an exciting development, Quad SLI really isn't for everyone. Unless you own a 30" LCD panel that supports the Extreme High Definition resolution of 2560x1600 and a PC with the fastest dual-core processor, it's unlikely for you to actually derive any benefit from Quad SLI.

In addition, Quad SLI will require a significant amount of power and cooling. Even using the new cooler and more efficient GeForce 7900 GTX GPU, these cards still use a lot of power and release a lot of heat. For them to run at full speed, the system's power supply and cooling must be validated to be able to handle the extra load.

Because of those considerations, NVIDIA will not be shipping any retail Quad SLI cards for now. Instead, they will work with system assemblers like Alienware and Dell to deliver Quad SLI PCs with the necessary components for Quad SLI to work, and for the users to actually enjoy its benefits, namely a display that will support Extreme HD.

Still, higher frame rate and higher resolutions isn't all that Quad SLI will allow you to do. NVIDIA also threw in additional rendering methods and faster anti-aliasing. Let's check them out!