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
Overall Performance Scaling With 4 GPUs
Before we present the percent scaling when moving from SLI / CrossFire to Quad-SLI / CrossFireX, we need to make note of a few things.
First, the 9800 GX2 is a higher performance part and is going to run into CPU limitations more readily than the 3870 X2. This means that sometimes scaling won’t reflect the true potential of the NVIDIA solution.
Second, anything over 50% scaling shows that the game is running on all four GPUs. However, less than 50% scaling doesn’t mean that all four GPUs are not doing work. On the contrary, if two GPUs don’t scale near linearly, moving from two to three will likely not scale linearly as well, meaning you could be seeing work done on 3 GPUs at less than 50% scaling up from the single-card dual-GPU solutions we have here. Then adding a fourth GPU might not even bring the percent high enough to make it clear that four GPUs matter.
What more than 50% scaling means is that all four GPUs absolutely matter and the game scales well with a Quad solution. With that in mind, lets take a look at the numbers.
So this becomes very interesting when you hear that NVIDIA claims 60% scaling with Quad-SLI in Crysis when running at Very High settings. We ran these numbers at High + Very High shaders, as we really didn’t expect that Very High would be any more than a slide show. We’ll take a look at this later. For now, suffice it to say that High settings plus Very High Shaders is CPU bound even at 1920x1200 under Crysis. Very High settings are also playable with Quad-SLI, but more on that later.
The Oblivion without AA numbers on NVIDIA are low because a single 9800 GX2 actually outperforms the Quad-SLI until you hit 2560x1600. This beast is made for high res gaming as long as bandwidth doesn’t kill it. 2560x1600 with Crysis isn’t here yet (unless you want to turn the quality way down), but this is only for people with 30” panels. If the only thing you want to buy 9800 GX2 Quad-SLI for is Crysis then by all means save the cash and get a 1920x1200 panel. We certainly don’t recommend such flagrant spending for one title though, and if you want your money’s worth, you’ll want the biggest display possible.
So, CrossFireX doesn’t scale at all in Crysis, all of our AMD cards started crashing out of the World in Conflict benchmark, and CrossFireX won’t run with OpenGL games yet. (AMD will release a driver supporting this at a later time.)
Neither quad solution hits every mark perfectly. We’ll take a look in a minute to see what happens with Crysis at higher settings, but in Oblivion - since performance is actually lower than AMD hardware - we wouldn’t expect to see any sort of system limitation here.
Facebook
Twitter
RSS
54 Comments
View All Comments
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?)