NVIDIA SLI Performance Preview with MSI's nForce4 SLI Motherboard
by Anand Lal Shimpi on October 29, 2004 5:06 AM EST- Posted in
- GPUs
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 :)
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bob661 - Friday, October 29, 2004 - link
I think some these guys are mad because the motherboard that suits their needs won't be considered "the best". For some, it's an image thing. If it isn't, then why do you care that SLI is even available? Just but the HF4 Ultra. Then there some that come here just to piss people off.bob661 - Friday, October 29, 2004 - link
Two GPU's on one card is more expensive and there would proabably be some heat issues.Pete - Friday, October 29, 2004 - link
Whoops. NV43 has only four ROPs, while NV40 has sixteen. So SLIed 6600GTs still have only half the ROPs as a single 6800GT. Mah bad.Tides - Friday, October 29, 2004 - link
SLI is meant for one thing, HIGH END. It's like spending 800 on an Athlon FX. Before now the option wasn't there, now it is. What's the problem?Pete - Friday, October 29, 2004 - link
Thanks for the preview, Anand (and MSI). One note:"At 1280 x 1024 we see something quite unusual, the 6800GT gains much more from SLI than the 6600GT. The 6800GT received a 63.5% performance boost from SLI while the 6600GT gets "only" a 45.7% improvement; given the beta nature of the drivers we'll avoid hypothesizing about why."
Not enough RAM? 12x10 4xAA is getting pretty RAM-intensive, no? That's one of the reasons I'm not that excited about SLI'ing two 6600GTs to the level of a 6800GT, but without the extra breathing room afforded by 256MB.
Two questions for you, too, Anand:
(1) The 6600GT is 500MHz core, 8 pipe, 4 ROP, 500MHz 128-bit memory. The 6800GT is 350MHz core, 16 pipe, eight ROP, 500MHz 256-bit memory. All else being equal, I'd have thought the SLI'ed 6600GTs would way outperform the 6800GT because they have the same specs and a 40% higher core clock. Is this just a matter of some efficiency lost due to SLI overhead?
(2) Is there a way to tell if the cards are rendering in "SLI" or AFR mode, or even to force one or the other? I'd be curious to know which helps which app more.
justauser - Friday, October 29, 2004 - link
I don't get it. Why not just put two GPUs on one 16x card. This bridge thing is so hokey.Tides - Friday, October 29, 2004 - link
Better yet don't buy the SLI version of the mobo, there ARE 3 versions of NF4 boards afterall.Tides - Friday, October 29, 2004 - link
Why are people complaining about an additional feature on motherboards, that you are no way forced to use? It's like having 2 agp slots on a motherboard, it's ROOM FOR UPGRADE. What's wrong with that?xsilver - Friday, October 29, 2004 - link
I think the performance boost is viable, only you need to know when to buy6600gt SLI is close to a 6800gt in most benchies and in the ones that aren't may be due to driver issues rather than performance... however 2X 6600gt does not equal 6800gt in price, but in say 12months time will a 6600gt + the price of the old 6600gt = or be less than the price of a 6800gt originally?
The new mainstream product in 12 months time should still perform less than a 6600gt in SLI
Think of it as getting as good card on "layaway" (am I saying this right? im not in the US :)
The other viability is of course having 2X 6800GT and saying I've got the best performance money can buy.... again you should not be superceded within 12-18 months
haris - Friday, October 29, 2004 - link
This is a horrible move by Nvidia. Several people have already stated so because of some of the main problems: Heat, noise, power requirements, and SLI may only work if the driver supports that specific game/engine. It might work out great for them since they will be able to get people to pay for two cards instead of just getting a more powerful single card solution which will work just as well if not better in every game. For most people, by the time they would be ready to upgrade a low-mid range card, it would probably still be more cost effective to just buy a new card.I love the performance boost as much as the next guy/girl, but I still think that this is just plain stupid.