Overclocking & Power Consumption
Most of us tend to use specialized tools for validating the stability of our overclocks. However, most of these utilities punish the CPU with severe workloads that go beyond the scope of normal applications. Intel's Kaby Lake platform includes the novel AVX Offset feature, which automatically dials back frequency when the CPU encounters taxing AVX instructions. Our MSI motherboard allows us to specify an offset in 100 MHz increments.
We didn't use the feature for our testing, but AVX Offset may come in useful if you're chasing the upper limits of your CPU's available headroom and need to account for the extra heat AVX instructions generate.
Unlocked multipliers simplify overclocking, and access to this ratio is the Core i3-7350K's biggest selling point. We overclocked the -7350K to 4.8 GHz by specifying a 48x multiplier, increasing voltage to 1.34V, and setting the Load Line Calibration to Level 4. After we found stable settings, we bumped up to 4.9 GHz and 1.355V.
These settings were stable during our entire test regimen, and after various stress tests. We were also able to boot into Windows and run light workloads at 5 GHz. However, intermittent instability and the need for 1.41V+ sent us back to a safer 4.9 GHz. Reports of -7350Ks capable of 5 GHz abound, but when it comes to the silicon lottery, your mileage may vary.
With Corsair's H100i v2 cooler sitting atop these mainstream CPUs, managing thermals wasn't a challenge. Although we recorded temperatures with AIDA, variance in the ambient temperature exaggerates the true difference between models and test runs. The chart does show that we didn't run into thermal limitations under heavy load, though (Intel's Core i3-7350K at 4.9 GHz peaks at 70°C).
We also measured power consumption during the stress test. AMD's Athlon X4 750K consumed over 100W. This is obviously well above the modern Intel processors, which all managed to stay below an average of 50W. The overclocked Core i3-7350K pulled an average of 49.5W, and the stock -7350K only consumed 38.5W. The Core i5-7600K averaged 46W, while our measurement tool reported the Core i5-7400 and -7500 using 33W and 30W, respectively.
