What are you doing to your CPUs? In my experience, CPUs are reliable enough to be nearly beyond reproach when troubleshooting a broken machine.
(Electrons are being pushed around by electric fields higher than 1 MV/m, and do smash into things ...)
I'm not complaining about my seven year old machines, but I'm not too sanguine about the current crop lasting as long ...
Out of my experience of ~8 PC assembled (super small sample size), 2 CPUs kissed bye right after the 3-yrs warranty period, 1 CPU DOA. the good thing is that good guy Intel replaced DOA CPU very fast.
You are really unlucky imho.