Windows 7 High CPU Usage

[Ogisha]

Okay so basically, I wanted to do a PC clean in which I strenghted the heatsink to the CPU, and when I booted into Windows 7 64 bit, I was getting idle 40-50% usage. And when I jumped into a game I barely got 20 fps and I had 100-150 fps (League of Legends). I cleaned the gpu, reinstalled it, reinstalled the cables from the PSU to the gpu and the motherboard, and I reinstalled the memory. Is there a solution to make my idle usage lower? My temps are ok, just the usage is high than before. I also did a clean install of Windows 7 64 bit and the problem is still there. I also reapplied the thermal paste and nothing has changed.
Specifications:
Biostar NF520D3 Motherboard
AMD Athlon X3 450 3.20GHz
8GB DDR3 1333MHz 
500 GB HDD

[Ogisha]

I fixed the problem, I reapplied the thermal paste again and the problem is gone. Now my CPU usage is 5% or less at idle, and the lag in games is gone. Hope this helpes someone who had the same problem.