Quad SLI with 9800 GX2: Pushing a System to its Limit
by Derek Wilson on March 25, 2008 9:00 AM EST- Posted in
- GPUs
Sometimes it’s the little quirks in life that sneak up on you and change the way you look at the world. The past couple weeks have done that in testing all this new high end gear. Sure, we’ve had our problems testing bleeding edge stuff before, but in putting all of this from CrossFireX through 9800 GX2 Quad SLI to the test, we’ve gotten ourselves lost in some other dimension of existence. It’s the only explanation really. Like Holmes would have said … whatever remains, however improbable … But I’m getting ahead of myself.
Skulltrail (the D5400XS Intel board we’re using that runs both CrossFire and SLI) rivals Frankenstein’s monster. From the 2x LGA775 sockets, FB-DIMMs, and NVIDIA nForce 100 PCIe chips, it’s not for the feint of heart. We’ve been determined to test on a single platform to compare CrossFire and SLI and trying to work out some kinks has given us a little trouble. AMD and NVIDIA and Intel have all worked with us to try and make things go more smoothly (thanks everyone), but there are still some things that we just can’t explain going on.
After loads of nearly useless testing and many conversations with different people, we set out on a trail of mystical discovery that has unlocked secrets of the universe here-to-fore untold. We’ll get to that in a bit, but first we’ve got to stop and take a look at what we are covering today.
Quad SLI. NVIDIA would like us to tell you it’s the new hotness. Certainly, without even opening a page of this review you should all know that this is the top of the top of the line and nothing is faster right now. But we do need to answer a few key questions about this $1200 setup: how does it scale from two GPUs to four, how does scaling compare to CrossFireX, and what kind of performance and value does this solution actually offer.
Honestly, we also have to acknowledge from our previous review of the 9800 GX2 that a single card is enough to run almost any game at maximum settings … that is, with the glaring exception of Crysis. Can Quad SLI change that? From what we saw in our CrossFireX testing from AMD, we would have thought not. However, NVIDIA has managed to get Crysis to scale across all four GPUs despite the interframe dependencies that make it so difficult. Is it enough to run Crysis at a decent resolution with all the eye candy turned on?
Let’s find out …
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Lorne - Tuesday, March 25, 2008 - link
I dissagree, Its in every developers best intrest to flex there emuscles when they can, It keeps the compotition between them going and also keeps prices down and the next techno advances coming to us.What I do like in alot of articals like this one and few others Ive read is the idea of the 3 hardware giants almost putting there heads together to solve a common problem area.
I wanted to put a quote here about a mention of Crysis being a single thred program but couldnt find it again, Did I read this wrong or is it true that 7 cores generaly sat idle, That would be bad programming not a harware limitation, A spec of how CPU utilisasion would also be good in the testing of these game demo's
The other comment I wanted to bring up was that FBDDR is slower then UBDDR, This could be the limiting factor and along with the formentioned why the swap to the N780 setup did better.
DerekWilson - Thursday, March 27, 2008 - link
"I wanted to put a quote here about a mention of Crysis being a single thred program but couldnt find it again, Did I read this wrong or is it true that 7 cores generaly sat idle, That would be bad programming not a harware limitation, A spec of how CPU utilisasion would also be good in the testing of these game demo's "it's not bad programming really... there are some things you just CAN'T split up to run in multiple threads without adding more sync overhead than performance from parallelism.
In any case, I did a quick test here ---
Crysis seems to have 3 main gameplay threads that do most of the heavy lifting. One bounces around at some pretty high utilization.
The other 5 threads are sitting at between 10 and 20% utilization.
Overall during gameplay on skulltrail we see total cpu utilization (average of all cores) at between 20% and 30%.
Moving beyond 4 cores should (and does) have zero impact on crysis with this information.
Two cores would likely even provide enough power to get by as two of the 3 cores that were more than 20% active sat betwenen 30% and 50% utilization each. Taking these two threads, if they were to run on one core, you'd never see more than 80% utilization.
tviceman - Tuesday, March 25, 2008 - link
How many people own skull trail platforms and have dual 9800GX2's? Ten. There are ten people that have this setup. For everyone else, it's a pipe dream so far fetched I think I'd have better chances winning the local lottery than owning this kind of system.Seriously though, there are significantly more cons than pros when using skull trail to benchmark video card performance. The raw power of 8 CPU's is great in theory but it's not translating in real world gaming applications (in some cases it's hurting).
Video card reviews would be served better with the fastest quad core CPU available, accompanied with the highest performance motherboard out, and an excellent CPU cooler to allow for maximum overclock.
charlie brown - Wednesday, April 2, 2008 - link
lol i agree no one will be able to afford this type of setup and if they did it is a waste of money.I agree that anandtech should post realistic equipment aimed at the enthusiastic croud rather than the rich kid with skulltrail. Try a qx9650 and e8500 chips and see what happens with the benches.
Graphics drivers are not mature enough for the multi sli technology, and games are not mature enough for 4 cores - this review makes spending all that money look nothing but a waste of hard earned cash!!!
SniperWulf - Tuesday, March 25, 2008 - link
I wholeheartedly agree. Not only is it too expensive, but its not practical. What enthusiast you know will actually buy a setup like that? None I know, and prolly not any on the forums either.Sure, you want to test apples to apples... But the true apples to apples test is the hardware that people can get off newegg or zzf. 780i's and x38s with cheap but good DDR2 and DDR3 (well skip the cheap on DDR3 lol) and a nice penryn core cpu
legoman666 - Tuesday, March 25, 2008 - link
The reason they use skulltrail on all of the recent graphics card benchmarks is because it's the only chipset that supports SLI and Crossfire. It's the only way you'll see an apples to apples comparison. So stop your complaining.Inkjammer - Tuesday, March 25, 2008 - link
I agree on that. My E6600 w/9800 GX2 doesn't get near the performance Anandtech got in their review. In fact, the performance was still great, but really disappointing by comparison. Then I realized the benchmark was done with 6+ more cores than I have.The huge CPU power slightly skews realistic performance expectations on an otherwise high end PC. Great for showing card potential, not great for performance you can realistically expect.
DerekWilson - Tuesday, March 25, 2008 - link
My numbers do not change if I pull one processor.I tested that -- number of cores do not matter. Only speed of the cores.
tviceman - Tuesday, March 25, 2008 - link
Which was along the lines of the primary the point I was making. Why not just use the highest performance motherboard available and a single quad core processor overclocked like crazy? At least, in that regard, you're still using the best processor and best mobo out, which both can be had in a custom system for what the (almost) general masses can afford.I think there is a time and place for extreme high end reviews. But when extremely high end hardware is used in EVERY review, applicable performance expectations to the masses don't exist. I like your reviews; you're thorough you write well, it's just that reading these types of reviews consistently is more like listening to an extremely wealthy individual brag about all his toys. And by no means am I calling you a snob - hardware reviews are a part of your job as well as a priviledge. I will, never in the next few years, meet anyone with a system set up to be as expensive as what hardware reviewers regularly test with.
tviceman - Tuesday, March 25, 2008 - link
Sorry I used the word review in every single sentence. I was typing in a hurry and I didn't proof read.And to once again make it clear, you do a great job reviewing hardware and I enjoy all the article put out by everyone on anandtech. I just question the use of extreme high end hardware in EVERY review (like the 9600GT vs. 3870, is the skull trail necessary there?)