Here's my situation, I have two x5460's (same stepping) that I modded to fit into a 775 socket. I installed the first one and it was running very hot (~68°C at idle) so I tried reseating and pinning down the heatsink with no change so I installed the other x5460 I have to make sure it wasn't a...
This has happened to me when trying to solder when the pads have not had the solder sufficiently cleaned, the old solder percentages must not mix well with the new solder (ie. lead free).