Weird Q9450 problem

I noticed lately that my computer hasnt been running as fast as it used to, nothing with the hardware has changed. I went out and bought a WD raptor hard drive yesterday to see if the hard drive was the problem, it is faster with the raptor but not as fast as what it should be, I didnt notice that much of a difference. My old hard drive was a WD 750 gig hard drive. I decided to run prime 95 to make sure all 4 cores were working and thats when I noticed something weird. When i ran coretemp during prime 95, all core 0, 1, and 3 are all running around the same temp, around 62C, but core 2 was about 15C cooler than the rest, even at idle it is about 15C cooler. When I was ocerclocking my CPU, that same core was always the one that would fail and get A BSOD, does this mean that core 2 is dead? it works in prime 95, but the temps are different than the other cores. Could this also be my computers performance issue?