I had an aging AMD dual core CPU in my mobo that I bought some 2/3 years ago. Playing games with the new GFX card it was clear the bottle neck was the CPU limiting FPS.
After some digging around I managed to find a AMD Phenom II X2 Dual Core 555 3.20GHz Black Edition [HDZ555WFGMBOX] at www.overclockers.co.uk for a very reasonable £60.
A great CPU with awesome over-clocking potential and the added bonus of possibly unlocking the additional 2 cores on it.
Once installed it was rather amazing the extra zing my machine had (along with the extra 2 GB ram, pushing it up to 4GB).
I was initially running Windows x64 in performance mode, which keeps the core clock speed at a constant 3200 GHz. This is turn kept the CPU running at a pretty high 52 degrees C with stock cooling.
The additional problem is that the stock cooling fan is rather rubbish and quiet noisy.
So I decided to replace it with the Arctic Cooling Freezer 7 Pro Rev 2 CPU Cooler
Installation on Asus M2A-VM HDMI for my new CPU took no more than 20 minutes and was simpler than I expected after reading some the reviews on overclockers.
I'd been running Windows 7 x64 in performance mode and been getting 51 degrees C with the stock fan. That dropped to 40-41 degrees with this cooler in place. (@ stock clock speed of 3.2 Ghz). Putting the performance on Win7 back to 'Balanced' results in a drop to 28-30 degrees. So far under load the maximum it has gone to is 50 Degrees.
What a brilliant bargain on both CPU and Cooler, with the additional ram my PC has a new lease of life for under £100.
As I speak to you my Rig is pulling only 115 Watts with Standard Performance settings on Windows 7 x64.