Originally Posted by Macmaster4k2
try reinstalling drivers? what brand is the graphics card? Also, it could be physx because you got it from an nvidia product and that could have nvidia drivers.
Check to see it the phenom is compatible with the HD 6770
Physx won't be causing the problem. I did a similar swap with another PC, took it from a GeForce 9500 GT which had included Physx and I uninstalled the nVidia drivers and left Physx and then installed the exact same model card (Radeon HD 6770) and it runs fine.
The other thing to ask is why XP 32bit? Your system has 4GB of RAM installed in addition to whatever the video card has. You're choking the system from achieving its full potential, and honestly, I doubt XP knows what to do with all that RAM flying about. You should upgrade to a 64 bit OS (Windows 7 preferably) ASAP.
Something else you can try is to adjust the fan speed on the card and see if it helps out - I just recently bought my 6770, and I did a lot of comparison shopping, and found that there were a lot of folks out there reporting issues with the 6770 from some vendors, so it could be related.