The CPU Scaling Story: From 2.66 GHz To 3.8 GHz
In both the Radeon HD 5870 and 5850 reviews, I benchmarked ATI’s latest and greatest on a Core i7 platform overclocked to 4 GHz, making absolutely sure we weren’t seeing any CPU-imposed bottlenecks. While this is great from a theoretical standpoint (what good are comparisons if they’re limited by a controllable variable, after all?), many readers asked to see those cards tested with a more “real-world” processor.
I took that feedback to heart and ran all of the numbers for this story on a Core i5-750—a reasonable $200 CPU on an Asus P7P55D Premium motherboard. But of course, that opened the door to the potential for processor limitations potentially making two cards appear similar in situations where they’re really not. Just to be sure we weren’t getting any of that here, I sampled a few games at different settings and found that the i5-750 at its default speed is truly ample.
At 1920x1200, a good compromise between the entry-level 1680x1050 and high-end 2560x1600 resolutions we like to use, you can see there’s virtually no difference between a stock Core i5-750 and the same CPU dialed in to 3.8 GHz. As you add anti-aliasing and increase graphical detail, the emphasis falls even harder on the GPU, so the benefit of a faster CPU would shrink even more.