Recently, my computer has slowed down significantly. I first thought it might be a software issue, so I formatted the disk, and installed Windows 7 again. This did not resolve the issue. In search of the answer, I installed CPU-Z and stared at the CPU's frequency for about 2 minutes. I noticed, that the Multiplier often jumps from 20 to 8. Is this normal? And if not, how can it be fixed?

P.S. I have reset the BIOS to it's default settings

Thank you for your time,