I'm a little confused what's going on here. I have a 6600K and an MSI Z170A Krait Gaming. At idle, according to hwmonitor, my CPU uncore power is 11W. This is just sitting at the desktop, web browsing, etc. But if I fire up a 3D game, it drops down to 3-6W.
What's going on here? I've checked all BIOS settings I can think of. I do run a 4.5Ghz overclock, and 4.5ghz ring speed on adaptive. I can't find my kill-a-watt right now, but I'm going to put it on that when I do. Is this just hwmon misreading things?
I also have a GTX 970 for a GPU.
EXPLANATION
UNCORE (= not core, not CPU) is easy to set. This post is valid for Skylake 6600k / 6700k on any motherboard (Gigabyte, Asus, etc.). Among other things, the Uncore Ratio relates to the frequency of the cache used by the CPU. And you have to manually set the Uncore Ratio in the BIOS of the motherboard because it remains stuck at the stock ratio of 35 (3.5 GHz) even after you have overclocked the CPU Clock Ratio way above that. To do that my Gigabyte z170 motherboard WRONGLY indicates to set the Uncore Ratio equal to or higher than CPU clock ratio. Why wrongly?
Think about it. The cache is a slave sub-process working for the CPU core master process that it is meant to assist by temporarily storing transient CPU data. Understandably, if you make the slave faster than its master, it will cause problems (!). So the BIOS should rather indicate to “set the Uncore ratio equal to or LOWER than CPU Clock Ratio”. That’s why it is perfectly stable when you leave it at its stock ratio of 35 (3.5 GHz) even after you have overclocked the CPU Clock ratio way above that (the Uncore Ratio is then much LOWER than the CPU Clock ratio). But then the cache (slave) lags considerably behind and puts a brake on the CPU (master) which is then badly in need of an assistant that can keep up with its much higher overclocked ratio. The master has no time to wait for the slave… which leads to timing problems. Doesn’t this make a lot more sense?
At stock values, both the CPU ratio and the Uncore ratio are set at 35 (3.5 GHz) and that’s very stable as, being that low, the frequency remains stable within tolerances. But after overclocking, the frequency starts to vary a lot more and the Uncore (slave) ratio can briefly peak (too much) above the CPU (master) ratio which often causes a blue screen with (of course) a timing error like “CLOCK_WATCHDOG_TIMEOUT”. At 4.5 GHz, my CPU Clock varies between 4495 and 4504 (not perfectly 4500). To avoid it, simply set the Uncore Ratio just ONE NOTCH BELOW (as often with overclocking) the CPU Clock Ratio. For example, if your CPU Clock Ratio = 45 (4.5 GHz), then set Uncore Ratio = 44 (one under). That way the Uncore Ratio will always stay BELOW the CPU Clock Ratio.
As a bonus, on 4.5 GHz, I also noticed via CPUID HWMonitor that VCore stayed at 1.332 V Max. So I reduced VCore in the BIOS from 1.35 V to 1.34 V and got less heat and lower POWER consumption.
CONCLUSION
Having reached a stable overclock with all green after 2 H on Prime95, boost performance by setting the Uncore Ratio just ONE NOTCH BELOW the CPU Clock Ratio you reached. For example, at a stable CPU Clock Ratio = 45 (4.5 GHz), set Uncore Ratio = 44 (one under). Next, as an extra bonus, reduce the VCore in the BIOS, for example from 1.35 V to 1.34 V. If you no longer get all green after 2 H on Prime95, come back to the previous VCore in the BIOS, for example from 1.34 V back to 1.35 V.
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