NVIDIA's GeForce 6 SLI: Demolishing Performance Barriers
by Anand Lal Shimpi on November 23, 2004 10:23 AM EST- Posted in
- GPUs
Final Words
From a performance standpoint, SLI is just about as good as it gets. If you have the budget for it, a pair of GeForce 6800GTs will let you run at 1600 x 1200 with 2X or 4X AA enabled in the latest games while still maintaining a very smooth gaming experience – something that no single card is able to do.
The GeForce 6600GT seemed to scale reasonably well, with a pair of 6600GTs outperforming a single 6800 Ultra in Doom 3 and Half Life 2. It doesn’t make too much sense to buy a pair of 6600GTs today however, as you’d be much better off getting a single 6800GT and upgrading to a second one down the road, which brings us to our next point, the upgrade value of SLI.
If NVIDIA is able to get their SLI certification program successful enough and if motherboard manufacturers are able to get SLI boards cheap enough, then the upgrade value of SLI is significant. We’ve already seen that going from a single $200 GeForce 6600GT to a pair of them offers performance greater than that of a single $400 GeForce 6800GT. Take into account that the price of these cards goes down over time and you’re looking at a pretty decent upgrade path for the future, requiring minimal investment today.
The upgrade path for 6800GT owners is even more enticing; if you’ve only got $400 to spend on a card today you can’t beat the 6800GT as a single card solution. Then, as the price of the 6800GT drops, it may become more attractive for you to upgrade to a second card rather than buying a next generation GPU. As long as we’re between DirectX cycles, SLI enables you to have the fastest most robust graphics setup out there without missing out on much.
While companies like ASUS, Gigabyte and MSI are working to get their boards out before the end of the year, it looks like the majority of manufacturers won’t have product on the streets until the first few months of 2005. We’d anticipate that by the middle of 2005, you’ll be able to purchase SLI motherboards for near mainstream Socket-939 prices, which should definitely drive for higher adoption and lower prices on SLI products (not to mention wider availability of NVIDIA certified SLI products).
The power requirements as well as the lack of NVIDIA certified SLI products out on the market today does trouble us a bit, but we’ll have to keep an eye out over the coming weeks to see how things change to better accommodate the introduction of SLI. At the same time, should SLI catch on, it has yet to be seen how NVIDIA and their partners will change pricing/availability strategies of older cards.
ATI will also have their own SLI chipsets and graphics cards in 2005, which should lend further credibility to SLI as a viable upgrade option.
The main thing to keep in mind that SLI is an option for those who want it; and whenever we have an option that offers a 40 – 70% performance increase where it counts, we welcome it with open arms (and wallets).
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bob661 - Tuesday, November 23, 2004 - link
I find it absolutely amazing that they were CPU limited using a 4000+.Avalon - Tuesday, November 23, 2004 - link
Anand, you keep saying that a 6600GT in SLI outperforms a 6800U in Doom 3 and HL2, but your benchmarks look partially wrong to be concluding that. It seems it would be more correct if you said that a 6600GT in SLI outperforms a single 6800U in lower res, lower bandwidth situations (such as 12x10 with low AA/AF, or less), but in high res and bandwidth situations (such as 16x12 with a bit of AA/AF), the 6600GT doesn't appear to be able to keep up at all with a single 6800U. Buyers will need to take that into consideration, to make sure that the video setup they will be purchasing will meet their needs specifically.lifeguard1999 - Tuesday, November 23, 2004 - link
One simple question: Are there Linux drivers that support SLI?Historically, people have talked about a setup either being CPU bound or GPU bound. That is no longer the case. With SLI it appears that the limiting factor is data. Simply put, there is not enough data for the dual GPU's to render. This is a common problem in parallel programming, especially when you are talking about thousands of processors. By increasing the amount of data for the GPU to render, one can see that SLI performs better.
For example, at 1600x1200, the increase is only 20% going from simgle 6800U to 6800U-SLI. Now by increasing the amount of work for the GPU to perform (1600x1200 with 4X AA and 8X AF), the performance increases 48% going from simgle 6800U to 6800U-SLI.
What this means is that game developers can now have Low, Medium, High, Ultra, and Ultra-SLI rendering modes in their games. :) What a nice "problem" to have.
In my line of work (Scientific Visualization) where we can have models up to hundreds of millions of polygons, SLI is going to cause a revolution in how we do business.
Alphafox78 - Tuesday, November 23, 2004 - link
wow, if I my LCD went to 1600x1200 SLI might help me slightly... I wonder what % of people actually play with the res that high. at 1280x1024 with my 6800GT AGP overclocked to ultra speeds with 4x aa and 8x anistropic I noticed no slowdowns in the game, smooth as can be for 95% of the game.GhandiInstinct - Tuesday, November 23, 2004 - link
Yes, great performance increase, but its too expensive to afford for most people. Unless you're 3 generations behind and need a new system chances are you'll buy this but not for people that have stabe up to par systems. This just isn't a wise investment when ATI's multi-gpu technology is right around the corner which doesn't limit you to the inferior Nvidia.OriginalReaper - Tuesday, November 23, 2004 - link
I dont see why 8xAA wasn't used. It's clearly not GPU limited at 4xAA 8xAF.blckgrffn - Tuesday, November 23, 2004 - link
I am glad that NVIDIAs drivers seem fairly mature already, hopefully they will have a new release out by the time SLI becomes "mainstream". It would have been awful had this real release been tainted by a lot of driver issues. So, the real point here is that if you really want performance, you have to drop $800 at some point? Wow. Two 6600GTs already are not the optimum choice for 1600*1200, so a 6800GT is what should be purchased now if you are really all about fps. Hmmm. I suppose I do know people who would like the incremental upgrade path, but I am not one of them when it comes to graphics cards - I sell my "old" one just before the new product cycle really starts appearing in quanities on the shelves and go for the new technology, and I am guessing that many who have $800 to spend on graphics cards would do something similar. I am jealous of those who will be able to spring for a big-power SLI setup out of pocket...dak - Tuesday, November 23, 2004 - link
I'm curious, is it possible to use two PCI-X video cards in these SLI boards, but not have them configured SLI? I have some applications that would benefit greatly from having two high end dual output cards in a single computer.....shabby - Tuesday, November 23, 2004 - link
Great article Anand, can you mention which psu you used to feed those hungry 6800 ultra's?Aquila76 - Tuesday, November 23, 2004 - link
Looks like SLI'd 6800GT's are a great option for now. I'm greatly awaiting ATI's Multi-Rendering products now. Can't wait for that benchmark setup!