My relatively new i7-4790K @ 4.00GHz has been exhibiting terrible performance since I bought it a few months ago.
The machine feels extremely sluggish. CPU utilization at rest, as reported by SysInternals Process Explorer is usually around 7%, and if I do as little as to run a browser and open up a page with a video or a little animation in it, it jumps to 30%; everything I do has considerable delays, for example IntelliJ IDEA has constant lag while typing; and most importantly, PassMark PerformanceTest is giving me CPU and Memory scores that are noticeably below world average.
An Intel i7-4790K at 4GHz is not supposed to be anywhere near world average. It is supposed to be far above that.
While troubleshooting things I ran Intel's "Extreme Tuning Utility" and saw that the machine is usually running at 800 MHz instead of 4 GHz, but it briefly jumps to 2.5 GHz or even higher when it has some serious work to do, but only on extremely rare occasions and for very brief periods of time. Also Intel's utility shows that no heat or power throttling whatsoever is taking place at any time, no matter how much I am taxing the CPU. So, cooling is not the culprit.
I tried various other things, like switching off Aero on Windows 7, to no avail.
What could be the cause of this terrible performance?