Why bus speed drops from 100 to 95mhz under Windows on my i5 4690k?

[ABab]

Hi all,

This problem occurs under Windows 8.1 (x64), while in bios everything looks fine. The bus speed should be ~100mhz but it keeps floating around 95mhz on idle, and 96mhz under 100% load and because of that cpu cant reach maximum speed. I tried to change power plan to high performance, and disabled all power saving options in bios (C3, C6/7, eist). With no effect. Can it be caused by some Intel drivers?

What's interesting Intel XTU does not see the lower clock.

[Hans_B_Intel]

Hi Wywar,

Where do you see the bus speed fluctuating or what tool are you using to monitor the CPU? I would assume that this is an issue with the software that you are using; the XTU would give more accurate information.

I found an article reporting this issue with CPU-Z:

http://www.overclock.net/t/1370045/whys-cpu-z-showing-100-bus-speed http://www.overclock.net/t/1370045/whys-cpu-z-showing-100-bus-speed