I’ve long observed that the best Haswell-based dies will reach 4.6 GHz at less than 1.30 V, and long heard reports of CPUs that were pushed beyond 1.30 V degrading over time. That is, they slowly become less stable at full speed, which eventually requires an underclock. We don’t want that to happen to our readers.
My strategy is to exceed 4.6 GHz at no more than 1.30 V, though that doesn’t often work. Finding 4.7 GHz stable only at voltages that slightly exceeded 1.30 V, I dialed in 4.6 GHz and started looking for the lowest core voltage that would support it.
I found complete 4.6 GHz stability at 1.24 V. The large voltage difference between 4.6 and 4.7 GHz indicates to me that 4.6 GHz was also a great place to stop. In fact, 1.24 V is less than the peak operational voltage of this CPU at its stock settings.
Scroll up a couple of images and you’ll find that I also pushed G.Skill’s DDR3-1866 C8 to DDR3-2400 C10. That setting was far easier to find, partly because my experience with this memory shows that it reaches top stability at 1.60 V. The other half of this overclocking ease comes from the MSI motherboard’s integrated DRAM timing slope, which appeared to slow memory timings by almost-precisely the amount needed to support the overclock. I was only able to reduce the command rate (from 2T to 1T) and tRAS (from 37 to 28) without causing instability.
I overclocked the GPU with similar ease, but with less enthusiasm. After finding that the default fan slope would support all stable overclocks, I reverted to Catalyst Control Center’s built-in overclocking tool. Though these overclocks won’t impress anyone, any further increases in GPU clock caused visual errors even at low temperatures, and any further increase in memory clock caused black screens.
Though I didn’t gain much by overclocking, I certainly beat last quarter’s build. On the other hand, the previous machine was beset by a CPU that needed 1.28 V to reach only 4.20 GHz and, lacking the advantage of Intel’s newest Devil’s Canyon improvements, couldn’t accept more voltage without throttling.