Not sure where they get them but I have been buying from them for years and never a problem.
CPU's arent noted for going bad unless they are o/c'ed or not vented right ( aka heat either way) so a used CPU is not something I have ever worried about.
Bought a lot of three digital cameras there a few years back. One went bad 2 months later and they replaced it, no questions asked.
I just wish they werent on the opposite side of the country from me, the shipping $ is not bad but the wait kills me.
Linear Mode
