NVIDIA SLI Performance Preview with MSI's nForce4 SLI Motherboard

Final Words

The performance advantages due to SLI are nothing to be disappointed with, using two GPUs NVIDIA is able to deliver next-generation graphics performance with today's cards. Keep in mind that our numbers were taken at relatively high resolutions with 4X AA enabled; without AA enabled and at lower resolutions the performance gains from SLI become much lower as you are far more CPU bound.

The GeForce 6600GT is the prime candidate for the SLI poster child as it is the most affordable card with SLI support from NVIDIA. Unfortunately our tests here today are more geared towards the higher end cards as the 6600GT, even in SLI mode, is still generally outperformed by a single 6800GT. At lower resolutions or with AA disabled, the performance of two 6600GTs would definitely be more similar to that of a single 6800GT. But the important thing to keep in mind here isn't what you can do with two cheaper cards and SLI, but rather the upgrade potential SLI offers. Buying a $200 6600GT today and upgrading to another one several months down the road, at a potentially much lower price, is a great way of getting the performance you want today while at the same time having a cheap upgrade path for when tomorrow's games come out.

The GeForce 6800GT in SLI mode truly skyrocketed to a new level of performance, but a very costly one. With a pair of 6800GTs selling for about the price of most users' upgrade budgets, we once again see more potential in the upgrade value of SLI rather than the initial purchase value. However, if you can afford it, a pair of 6800GTs in SLI mode will definitely offer some serious performance in all of today's games. Interestingly enough, spending close to $1000 on graphics cards still won't let you play at 1600 x 1200 with 4X AA at over 100 fps in Doom 3; but if you're willing to settle, over 60 fps is a piece of cake.

Although motherboard and graphics support for SLI is definitely close to being ready, we are not so certain about the maturity of the drivers. NVIDIA's own tests were conducted under three applications: Doom 3, Halo and 3dmark 05. Although our own tests added two more benchmarks, they didn't run without their fair share of display issues. The complexity of the SLI driver and ensuring game compatibility is undoubtedly a major factor in the release date of SLI. We are also hearing that chipset availability is a bit on the limited side for nForce4 SLI, with most manufacturers planning on shipping boards in early 2005. ASUS and MSI both seem to be on track to a release by the end of 2004, which will definitely give them the lead if NVIDIA can get finalized drivers out in time.

All is not quiet on the ATI front though, rumor has it that they are also planning on some SLI-like solutions on both the chipset and GPU side. Given the flexibility of PCI Express to support multiple high-bandwidth slots for graphics, we would think that there's no reason (other than driver support) to not want to have SLI support within a product family. The introduction of SLI could lengthen the GPU product cycles as performance can be guaranteed for much longer, but it could also increase the expectations of upcoming GPUs like NV50 and R500. We would not be too surprised if supply issues of many of the popular SLI cards developed right before the launch of a new GPU to prevent a lackluster introduction.

In the end we're rather pleased with SLI as it promises to increase the life span of your graphics card investment, something that we've been dying to have for quite some time. We will be sure to do a full review on the final shipping SLI motherboards and GPUs when they are available, but until then we hope you've enjoyed our preview.

Very special thanks goes out to Vincent and Iris of MSI for putting themselves and their engineers through hell in order to make this review possible. You would not believe how difficult this little benchmarking opportunity was to put together :)