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
(Not so) Final Words
Unfortunately, we can’t really draw a fair final conclusion from the data we have here. Certainly this is an expensive solution, and it is absolutely not for everyone. But does it fill the needs of those who would want it and could afford it? Maybe and maybe not.
In almost every game other than Crysis, we don’t have a need to move beyond one 9800 GX2 (or 8800 GT/GTS/GTX/Ultra SLI). And in Crysis, we aren’t simply going to trust NVIDIA when they say we should see 60% scaling. We need to actually make it happen ourselves. The fact that we’ve run into some pretty strange problems doesn’t bode well for the solution in general, but we are willing to see what we can do to make it perform near to what we expect before we cast final judgment.
At the same time, that final judgment must include all the facts about what you gain from Quad SLI for the money. If it makes Crysis smooth as butter at Very High settings (it is actually playable even with the 40 average FPS system limitation), then that is something. But $1200 for a Crysis accelerator is a bit of overkill. NVIDIA has made the point to me that $1200 spent on graphics cards is better placed than $1200 spent on an Extreme Edition CPU. That isn’t a particularly compelling argument for us as I don’t believe we have ever recommended the purchase of an Extreme Edition processor (except for overclocking enthusiasts, perhaps). You certainly don’t get what you pay for unless you really need it for a specific CPU heavy workload. Content creation, engineering, math, and workstation applications might be a good fit, but certainly not gaming and especially not in a world where the more extreme you get the more cores you have.
Which brings me to a side rant. Parallelism is a good thing, but neither Intel nor AMD can ignore the single-threaded code path. Not everything can be split up easily, and every thread will always be limited in performance by the speed of the core it is running on. Of course, specialized cores on a heterogeneous processor would help, as would dedicated hardware. That just makes us lament the death of the PPU through the NVIDIA acquisition even more. But I digress.
On the topic of 9800 GX2 Quad SLI, there are benefits aside from the potential of Crysis that we haven’t covered here. NVIDIA has enabled AA on S.T.A.L.K.E.R., but it is very processing and memory heavy. Quad SLI could enable playable frame rates at higher resolutions with 2xAA enabled. With Clear Sky coming out soon, this could be a good thing for fans. You also get SLI AA modes. These do offer a benefit, but AA has diminishing returns at higher resolutions, and especially at higher AA levels. We will be testing SLI AA again at some point, but we want to look at both image quality and performance when we do so.
These cards also act as incredible space heaters. That may not be important right now with summer coming on, but any of our readers that live at the North Pole (Hi Santa! I've been good!) or in Antarctica (sentient penguins running Linux, for example) might appreciate the ability to turn down the thermostat while they sit next to their toasty Quad SLI system.
The bottom line right now is that this is not a solution for most people. Unless we see great scaling in Crysis, there are only a few other compelling features that can currently be enabled through the use of Quad SLI. Sure, it might handle future games with ease, but we always advise against trying to future proof when it comes to graphics. That’s always a path that leads to heartache and the hemorrhaging of money. Just ask previous 7950 GX2 Quad SLI owners about how happy they've been with support and performance over the past year. If you aren’t obsessed with Crysis, skip it. If you are obsessed with Crysis, we’ll get back to you with some numbers on what performance is like once we find a system we can get some headroom on: I’ll have 790i this week and I’ll be hard at work testing it 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?)