I have my 3770k @ 4.4 Ghz, 1.2v And when ever i run prime95 Only core 123 Will go, However at low load tasks it works fine... Is this just a bad overclock or did i Ruin it?
Also temps dont go higher that 67c (h100i)
Does core 0 show up in coretemp? if not it may be kinda like what happened to me before when I was playing around in msconfig. under advanced boot options make sure you dont have a setting for how many cores to use. just make sure they are both unchecked, both processors and ram. This is just assuming you may have been messing around with boot settings aswell as doing a OC. This may be of no help at all, just proposing an idea.