NVIDIA's GeForce 6 SLI: Demolishing Performance Barriers
by Anand Lal Shimpi on November 23, 2004 10:23 AM EST- Posted in
- GPUs
Doom 3 Performance
As you can expect, SLI offers no benefits at 1024 x 768, but as early as 1280 x 1024 we start to see some reasonable performance gains. The 6800 Ultra gets a 22% increase in performance, while the 6800GT gets a slightly bigger bump of 26% thanks to SLI. The big winner here is the GeForce 6600GT whose frame rate jumps 43% from 63.6 up to 91.1 thanks to SLI. Here we begin to see some of the upgrade potential of SLI, with two 6600GTs offering slightly greater performance than a single GeForce 6800 Ultra at 1280 x 1024.
At 1600 x 1200 the 6800 Ultra sees a 39% performance increase in SLI mode, breaking the 100 fps barrier in Doom 3’s built in demo. The 6800GT gets even more of a performance boost at 53%, bringing it to within striking distance of a SLI 6800 Ultra setup. The 6600GT also becomes much more playable at 1600 x 1200 with SLI enabled.
Enabling Antialiasing simply increases the benefits of SLI. Now at 1024 x 768 there is a performance advantage to having two GPUs, and for the 6800 Ultra that’s a 34% increase in performance. Once again, the margins of improvement get better as you move to slower GPUs – 36% for the 6800GT and 66% for the 6600GT. At 1024 x 768 with 4X AA the two 6600GTs manage to offer performance that’s just slightly faster than a single 6800GT.
Going up in resolution we continue to see some impressive gains, but what matters here isn’t that SLI results in a 63% performance increase for the 6800 Ultra and 72% for a 6800GT, what matters is that SLI makes 1280 x 1024 with 4X AA and 8X AF very smooth, something that was not possible with only a single card. Despite the performance improvement, two 6600GTs are not able to pull ahead of even a single 6800 Ultra in this test, which shows you some of the limits of SLI. While the 6600GT in SLI mode does much better than a single 6800 Ultra at “lower” resolutions like 1280 x 1024 with AA disabled, turning on antialiasing still preys on the bandwidth and fillrate limitations of an 8-pipe 6600GT with only 16GB/s of memory bandwidth.
What’s important to note here is that the recommendation varies greatly based on resolution. While the 6800GT does incredibly well paired up with another card, the 6600GT only offers better performance than a single 6800 Ultra at non-AA resolutions. As soon as you enable AA, even a pair of 6600GTs isn’t faster than a single 6800 Ultra (or GT).
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Kolbe - Monday, February 14, 2005 - link
BUYER BEWARE!!first, I have this ASUS motherboard and two GigaByte 6600GT's. AFter countless hours of trying to get this to work AND of course upgrading bios and drivers, I came to find out that these two gigabyte cards are not certified by Nvidia and they will not work in the sli mode on this ASUS board. ASUS has not returned my calls or my emails, but gigabyte, bless their hearts, wrote me back and said in essence: "our 6600GT cards work on OUR board" so too bad. Thank God for Newegg and their awesome return policy. I am returning these two and getting one 6800 GT, but of course, not from Gigabyte!
mashie - Sunday, December 5, 2004 - link
It would be nice to see tests at 2048x1536. After all if you can afford the videocards for SLI I bet you can get a proper monitor as well ;)Denial - Thursday, December 2, 2004 - link
Again, why no vanilla 6800's? How would they compete with the 6600GT's in SLI? This is starting to get rediculous.nserra - Friday, November 26, 2004 - link
Sorry forgot link.http://graphics.tomshardware.com/graphic/20041123/...
nserra - Friday, November 26, 2004 - link
#69 Yeah i agree.But let me tell you i already see something that SLI will give me.
Having a 6600 and a X700 on the same PC.
piroroadkill - Friday, November 26, 2004 - link
I don't know if anyone's said this, but SLI is an absolutely stupid idea, why on earth don't they take the 3Dfx Voodoo5 approach and just stick two GPUs on one card? Surely this would yield similar benefits without special mobo requirements.. 16x PCIe is easily enough bandwidth to cope... then just double the amount of RAM on the card and surely this is more viable solution? sure it'd be an insanely costly card, but still cheaper than an SLI setup, and lets face it, once a single card can outpace your shiny new SLI setup, that SLI setup is going to look poor value for money and you're just going to waste both cards, it seems obscene.stance - Thursday, November 25, 2004 - link
will the new duel core amd cpus that come out mext year be supported by this motherboardstance - Thursday, November 25, 2004 - link
tombman - Wednesday, November 24, 2004 - link
ANAND, please answer:1.) Can you really force SLI for games with no profile in the driver?
2.) please make 2048x1536 or higher Tests (my CRT can da 2304x1440 :D)
3.) please make 8xAA Tests
4.) please check if HDR (high dynamic range rendering) in far cry works in SLI mode (other sites say no)
Especially # 1.) is very important.
If only games with a profile can run in SLI mode, SLI will not become very popular imo. We know nvidia- they will only have profiles for benchmarks and most common hyped games. For not so popular games there surely will be no profiles...
thx
tombman - Wednesday, November 24, 2004 - link
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