If you are getting errors in prime SmallFFT immediately, your Vcore is too low for that clockspeed.
Seems like the CPUs you got aren't very good, just like my E5440 were a great disappointment.
If you open up CPU-Z, what revision does it show? Should show something like C0 or C1, if it's B something you have your answer, B step Harpers suck (in my experience anyway)