Choosing a Gaming CPU: Single + Multi-GPU at 1440p, April 2013
by Ian Cutress on May 8, 2013 10:00 AM ESTSleeping Dogs
While not necessarily a game on everybody’s lips, Sleeping Dogs is a strenuous game with a pretty hardcore benchmark that scales well with additional GPU power. The team over at Adrenaline.com.br are supreme for making an easy to use benchmark GUI, allowing a numpty like me to charge ahead with a set of four 1440p runs with maximum graphical settings.
One 7970
Sleeping Dogs seems to tax the CPU so little that the only CPU that falls behind by the smallest of margins is an E6400 (and the G465 which would not run the benchmark). Intel visually takes all the top spots, but AMD is all in the mix with less than 0.5 FPS splitting an X2-555 BE and an i7-3770K.
Two 7970s
A split starts to develop between Intel and AMD again, although you would be hard pressed to choose between the CPUs as everything above an i3-3225 scores 50-56 FPS. The X2-555 BE unfortunately drops off, suggesting that Sleeping Dogs is a fan of the cores and this little CPU is a lacking.
Three 7970s
At three GPUs the gap is there, with the best Intel processors over 10% ahead of the best AMD. Neither PCIe lane allocation or memory seems to be playing a part, just a case of threads then single thread performance.
Four 7970s
Despite our Beast machine having double the threads, an i7-3960X in PCIe 3.0 mode takes top spot.
It is worth noting the scaling in Sleeping Dogs. The i7-3960X moved from 28.2 -> 56.23 -> 80.85 -> 101.15 FPS, achieving +71% increase of a single card moving from 3 to 4. This speaks of a well written game more than anything.
One 580
There is almost nothing to separate every CPU when using a single GTX 580.
Two 580s
Same thing with two GTX 580s – even an X2-555 BE is within 1 FPS (3%) of an i7-3960X.
Sleeping Dogs Conclusion
Due to the successful scaling and GPU limited nature of Sleeping Dogs, almost any CPU you throw at it will get the same result. When you move into three GPUs or more territory, it seems that having the single thread CPU speed of an Intel processor gets a few more FPS at the end of the day.
Facebook
Twitter
RSS
242 Comments
View All Comments
Patrese - Wednesday, May 8, 2013 - link
Awesome article, thanks! Is it possible to include some sort of gaming physics testing? Now that PhysX is beginning to catch some momentum, I'd be great to see if a 8-module AMD processor handles physics stuff better than a 4-core comparable Intel one, and at what point does a dedicated physics card starts to make sense, if at all.I’d be also nice if a “mainstream gaming” article could be made too. Benchmarks at 1080p with cards like the 660Ti and 7850, for instance. No need for 3 way SLI/CF on those, so you'll not need as much time in Narnia. :)
araczynski - Wednesday, May 8, 2013 - link
interesting read, although i find it too focused to be of much general use (or useful future reference). i'd like to have seen for example how an E8500 holds up (too big of a gap between E6500 and i52500), as well as at least ONE game i would even bother playing (skyrim/witcher/etc). and of course like you mentioned, even a slightly bigger sampling of graphics cards. (i think you mentioned that).anywho, i realize this wasn't meant to be anything exhaustive (i do appreciate having the CPU/GPU benches available here as a good reference though), and i do like the detail/explanation length you went into.
so thanks :)
xinthius - Wednesday, May 8, 2013 - link
But AMD offers good price to performance at lower tiers, they should be recommend.yougotkicked - Wednesday, May 8, 2013 - link
Regarding your comments on the role of artificial intelligence in game performance/programming: I've just finished a course in AI, and while implementations may vary quite a bit from game to game, many AI programs can be reduced to highly-parallel brute-force computation, simply evaluating the resulting states of many potential decisions for a numerical representation of their desirability, then selecting the best option from the set of evaluated actions. Obviously this is something that will vary greatly from game to game, but in games with many independent AI managed elements, I would expect a certain amount of the processing to be offloaded to the GPU.Other than that I agree with you on the demands of AI in games; my professor (who specializes in game AI and has experience in the industry) said that the AI is usually given about 10% of the CPU time in a game, so it's rarely a limiting factor.
I'm still working through the whole article (really enjoying it so far) so I'm sure I'll have many more comments/questions later.
IanCutress - Wednesday, May 8, 2013 - link
Based on previous CUDA experience, CUDA doesn't like a lot of IF statements in its routines. So if you're offloading different AI parts onto the GPU, unless all the elements are being put through the same set of if commands (and states), it won't work too well, with some warps taking a lot longer than others if there is large branch deviation. It's a task suited to MIMD environments, like a CPU. Then again, it really depends on the game. Clever AI is already here, because we confine it to a self-created system. One could argue that the bots in CounterStrike are not particularly smart, but the system can put their accuracy up to 100% to make it harder. It's a lot of give and take, perhaps. It is times like these I wish I did CompSci rather than Chemistry :) I need to take one of those MIT online AI courses. You know, inbetween testing!Ian
yougotkicked - Wednesday, May 8, 2013 - link
I suppose conditionals would make offloading some AI components to the GPU impractical, but there still remains a subset of AI computations which seem very GPU friendly to me. State evaluation functions seems like a prime example, the CPU would be responsible for deciding which options to evaluate, building an array of states to be evaluated by the GPU. These situations probably don't come up very often in FPSs, but in something like Civilization I can see it being quite common.I've actually got to head over to that class now, I'll ask the professor if he knows of any AI's using GPU computing in modern games.
airmantharp - Wednesday, May 8, 2013 - link
Like Ian said, GPU's aren't good 'branch' processors, but I do see where you're coming from. Things like real physics, audio environment maps, and pre-render lighting maps could be fed to AI routines running on the CPU. This would allow for a much greater 'simulation awareness' for AI actions.yougotkicked - Wednesday, May 8, 2013 - link
I spoke with my professor and he said that as far as he knows, many people have discussed to prospect of using GPU's for AI, but nobody has actually done so yet. He's going to ask some friends of his at some major game studios to see if they are working on it.He did agree with me that there are some aspects that could be computed on a GPU, but a lot of the existing AI methods are inherently sequential, so offloading it to the GPU will require new algorithms in many cases.
TheQweaker - Thursday, May 9, 2013 - link
You may wish to check nVidia's GTC conference web site where you can find some GPU AI Research. Also, nVidia published various PDF slides on GPU Path Planning.If you look deeper in some specific AI Domains such as, say, AI Planning (first used in F.E.A.R. in 2005, lately used in KillZone 3 and Transformers 3: The Fall of the Cybertron) you can find papers investigating the use of GPUs.
On of the bottom line of current GPU AI research is that GPUs crunch large numbers of data very fast so, currently, there is not much hope in using the many GPU threads for tiny amounts of data of state space search.
Hoping this helps.
-- The Qweaker.
yougotkicked - Thursday, May 9, 2013 - link
Thanks for pointing me towards those papers, they look pretty interesting and I've been looking for a topic to write my final paper on ;)