Is the processor or the graphics card the limiting factor in a game? PC Games Hardware tested the three popular games Crysis Warhead, Far Cry 2 and Fallout 3 to check which component is the chock in which situation.
When upgrading your system you might have asked yourself if your processor can keep the pace of the new graphics card or if you should change the CPU, too. It is often reported that the 3D accelerator is more important and that a fast CPU is not necessarily required. We checked this assumption with 25 combinations and three popular games. 20 GPU-CPU setups tested: Summary
Crysis Warhead lives up to its reputation: The graphics card definitely is the limiting factor. Taking the results of the Athlon 64 X2 5000+ as a base, the framerate is slightly increased when the game is run on a Core 2 Duo E 6600, but practically this benefit is insignificant. If you want to speed up Crysis Warhead, you primarily should upgrade the graphics card.
In the RPG Fallout 3 with the HD Texture Pack only the Radeon HD 3870 is slowing down all CPUs, even the Radeon HD 4850 is accelerated by 15 percent if combined with the core i7-940, although such a high-end processor is not necessary. But a Radeon HD 4870 or Geforce GTX 285 should at least be coupled with a Core 2 Quad or Phenom II with 3.0 GHz.
Far Cry 2 is rather CPU limited - for a FPS game. Even the HD 3870 receives a performance benefit of about 15 percent when the Athlon 64 X2 5000+ is replaced by the Core 2 Duo E6600. The Radeon HD 4850 doesn't really benefit from a better CPU, but the Radeon HD 4870 gets a 5 percent bonus when combined with a Core i7-940 instead of a Phenom II X4 940 - the Geforce GTX 285 is 13 percent faster in this case. Practically this means that the GTX 285 receive almost twice the fps with a Core i7-940 than with an Athlon 64 X2 5000+.
At this point we would like to note that higher settings, like 4x MSAA and 16:1 AF for example, push the limitation further into the direction of the graphics card. High-end graphics cards nevertheless benefit from a fast CPU and this applies to multi-GPU setups even more so.
20 GPU-CPU setups tested: Conclusion
Without a fast graphics card modern games don't run smooth, but without a capable CPU on the other hand the performance of high-end graphics cards is lowered noticeably. While a 3D accelerator like a Radeon HD 4850 or a GTS 250 is satisfied with a Core 2 Quad Q6600 or Phenom X4 9950 BE, a Radeon HD 4890 or Geforce GTX 285 can deliver the full potential only in combination with a Phenom II X4 955 respectively a Core 2 Quad Q9650 or a faster processor - but only if you don't use exaggerated graphics settings.