yes i did, i had an a4 4300 apu, just installed the a8 today with a cooler master heatsink
Ahh ok I Think I have an Idea, You may need to tell windows to boot up with all 4 cores of the cpu instead of the 2 that it usually does.
Bring up "System configuration untility" (type in (winodws 7/vista ) The search bar "msconfig" or (xp) click run then type msconfig)
Then head to the BOOT.INI and click advance options.
and see if the "NUMPROC" is checked or not.
If checked. Uncheck it then reboot. It will limit the number of cores you are able to uses in windows.