The Game Rundown: Finding CPU/GPU Bottlenecks, Part 2

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We're back with Part 2 of our bottleneck exploration in a mainstream gaming PC equipped with a Core i5 and GeForce GTX 460, ready to dive into test results from ten additional games. All of the results are summarized and analyzed in our conclusion.

Conclusion: A Trend Toward 3+ Cores

The latest 3D engines aren't doing Intel or AMD any favors. Somehow, something seems a bit off here. When most games used DirectX 9, you needed a really fast CPU, and these weren't terribly common before the 65 nm fab node due to thermal issues. Transitions to 65, and then 45 nm allowed processor manufacturers and overclockers to accelerate clock frequencies, making 3.5 GHz a breeze with most CPUs.

But the newer DirectX 10 and 11 games don't really need this speed. This change snuck up on us, making CPU overclocking for 3D games rather meaningless at the mainstream level. Of the 20 games tested in this article, only 10 respond at all to CPU overclocking when we used a GeForce GTX 460 graphics card. Seven of them show only small reactions. Just three show a small frame rate increase. Now, this situation might be completely different at lower resolutions, but the Radeon HD 5800-class monitors, the GeForce GTX 460, and HD resolution LCD monitors are slowly becoming standard gaming equipment.

The following table provides an overview of all the test results so that you can check whether your PC is ready for the tested games or if you need to upgrade something. If you are looking for an upgrade, we show what you should replace first. All of the games deliver higher frame rates with better graphics cards. The average optimal number of CPU cores suggested by the test results is 2.75, showing a clear trend towards at least three CPU cores. The age of dual-core CPUs is certainly not over yet, since DirectX 11 yet again puts the focus on graphics card performance. But with the help of better supply and pricing, the market is trending toward quad-core CPUs nonetheless (or at least dual-core chips with Hyper-Threading). Overclocking the CPU is quite pointless when playing games with high quality graphics settings and HD resolutions--unless you already own a pair of flagship graphics cards rendering cooperatively able to shift the bottleneck back to the host processor.

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Games and Impact FactorsGPU Performance ImpactRecommended Number of CPU CoresGame Response to CPU Overclocking
Alien vs. Predatoryes1no
Alpha Protocolyes2no
Anno 1404yes2no
Avataryes4no
Battlefield: Bad Company 2yes4somewhat
Bioshock 2yes2somewhat
Call of Duty: Modern Warfare 2yes2somewhat
Divitiny 2: Ego Draconisyes2no
Dragon Age: Originsyes4somewhat
GTA 4 EFLCyes4yes
Just Cause 2yes2no
Kane & Lynch 2yes2no
Left 4 Dead 2yes4yes
Mass Effect 2yes4somewhat
Metro 2033yes2no
Prince of Persia: Forgotten Sandsyes2somewhat
Stalker Call of Pripyatyes2somewhat
StarCraft IIyes4no
Supreme Commander 2yes4yes
Wolfensteinyes2no

Giving a straight answer regarding the amount of graphics memory you need is difficult. The games adapt. If less memory is available, less is often used. The feeling we get is that the 768 MB of our Nvidia GeForce GTX 460 graphics card is already starting to feel somewhat insufficient, although it's still fine for most games, so long as you aren't cranking up the anti-aliasing. At a 1920x1200 resolution, 8xAA, and 16xAF in a DirectX 11 game, you should aim for at least 1 GB of graphics memory.

The question of whether the CPU or GPU is most important is easily answered. If you don't have a multi-core CPU, then upgrade it. If you have a dual-core CPU at around 3 GHz, then invest your money into a graphics card, as most games are GPU-limited. This is not something that will change with new DirectX 11 games.

Tino Kreiss
93 Comments Comment from the forums
  • nativeson8803
    It's disappointing to see that devs still aren't taking advantage of multiple cores like they could.
    Reply
  • KingArcher
    Would there be any performance difference between windows 7 32bit and 64bit?
    Assuming you use the same amount of RAM .
    Reply
  • slayvus
    Great run down guys. I would of liked to see a three core benchmark thrown in there, but what can you expect from a dual core with HT.

    @KingArcher Unless the program was designed for x64, you had more than 4GB of unused RAM that the game could use and could use more than 4GB I highly doubt whether or not your on x86 or x64 would matter.

    @nativeson8803 What difference would it make on games that are still GPU limited at two cores? Even then, there were games limited by the GPU at four cores. Taking advantage of a CPU with four cores or more is going to be hard when you need more GPU to get more frame rates.
    Reply
  • palladin9479
    @Slayvus almost true. The difference would be @2 GB of available memory. NT x86 kernel only allows an application to access 2GB of address space with the other 2GB reserved for kernel use. In NT x86 world each application can only access 2GB of memory, with the application getting rather unstable once it goes over 1.8 GB. This limitation also applies to the NT x64 kernel running a 32-bit problem through WOW64. Its something left over from the NT 4.0 / 5.0 world.
    Reply
  • archange
    Just keep in mind that these result are relevant in the context of using the GTX 460 768 MB, which is the real bottleneck here. Better GPUs and/or multi GPU setups would shift the bottleneck towards the CPU.

    In the end, it's all about finding the perfect balance in hardware. If you want my advice, pair the GTX 460 768 MB with a fast dual core, but get a good quad with higher end model GPUs.
    Reply
  • deisu
    This methodology should be used to new cpu/gpus/games reviews.
    Reply
  • I'd like to see them test the first Supreme Commander.

    It still taxes the most powerful systems
    Reply
  • They should have used Phenom II X6 and test with 1/2/3/4/6 cores enabled. This made me want more of this because there aren't any 6-core benchmarks.
    Make a Part 3.
    Reply
  • Mobutu
    +1 deisu
    Reply
  • lashabane
    archangeJust keep in mind that these result are relevant in the context of using the GTX 460 768 MB, which is the real bottleneck here. Better GPUs and/or multi GPU setups would shift the bottleneck towards the CPU.In the end, it's all about finding the perfect balance in hardware. If you want my advice, pair the GTX 460 768 MB with a fast dual core, but get a good quad with higher end model GPUs.I totally agree with archange. I understand that you're trying to go for the "norm", but if you're looking for bottlenecks, you need to remove said bottlenecks to see where it truly lays. Start with a quad core clocked at ~3.5ghz and swap out gfx from there. Push and push to see where it truly lays instead of going for a baseline. Although you can use that baseline to see what the "average" person might use. If the article is truly about the bottleneck, use something beefier than the 460.
    Reply