Could be a bad fan, or could be an overheating CPU. If you open your case, clear out any dust, and run the CPU fan at 100% through AMD OverDrive, does it still get to those temperatures? 125F (51C) is high, but not the limit for that CPU. Try the open-case, clearing the dust, and ramping the fan up to 100% to see if it's just a bad fan, or a bad CPU. If the case being off and fan at 100% takes care of it, look at your case ventilation instead of the CPU/fan as the potential cause.
AMD Customer Care
The information presented in this document is for informational purposes only and may contain technical inaccuracies, omissions and typographical errors. Links to third party sites are for convenience only, and no endorsement is implied.