RE: Precision T5500 Pb7 Error
I think it's important to remember that the dual CPU set up is fairly complicated. If everything's not perfect it just won't work. You can read about my personal experiences with this here: en.community.dell.com/.../21016701
It's a hard nut to crack honestly because there's a number of things that it could legitimately be. For me, in spite of the fact that I swapped CPUs and it booted and ran with both there was one that's very slightly damaged and so it was no longer a perfect match. Let me make this clear, my CPU was NOT dead. Just very slightly broken and therefore a mismatch.
It wasn't badly broken as I ran for some time with each of them individually with no issues at all, but it seems that it doesn't take much, just a little bit of damage to throw the Pb7 error code.