I have an Intel 6850K overclocked to 4.3GHz on all cores that has been running with no problems for long, however I suspect after some Windows updates I couldn't get it to reach these frequencies in Windows. The BIOS (Asus Rampage V Edition 10) keeps the correct settings, reports the correct voltages, everything seems to be OK but once in Windows it goes only to 3.8GHz. BIOS is adjusted to keep Asus and not Intel Turbo settings, however I believe this somehow changes in Windows and I get the core clock down to a little higher than stock. The weird thing is that all voltages in Windows are the same as in BIOS and so is the RAM XMP profile - 3.2GHz. The only change is the core clock down to up to 3.8GHz (3.6 stock). Even Intel's default Turbo clock is 4GHz, not really certain why it goes to 3.8GHz. Asus has a Windows overclocking utility that I used to manually change the core clock back to 4.3GHz which however only worked until I restarted. Windows Power Manager is in a Balanced mode where CPU state is from 5 to 100% and I don't see a reason for the downclock there. Also I deactivated Intel Turbo in-Windows settings and restarted and again the CPU core didn't rise above 3.8GHz. Shall I clear CMOS? What may be causing this behaviour? I used HWInfo and CPU-Z reporting the same.