Try the Intel Burn test by Agent God, or the LinX, they put loads of stress on the CPU and can be pretty conclusive... do max test and about 20-30 loops (preferably 64bit OS)... so about finished in one hour... OCCT is also over and done in 2 hours...

Yet again I have to say that there's no 100% bulletproof test... running several (not at the same time ofcourse) might be more reassuring