maxijet? huh?
anyways, if it was SADS, "sudden athlon death sydrome" chances are it would have died for no reason at all, but since it happened while taking a heatsink/waterblock off and putting something back on, there are sevral possibilities:
1.)the core may be cracked,chipped,crushed, or damaged
2.)You may have bent one of the pins
3.)Some conductive thermal compound is shorting out a bridge
4.)The heatsink may not have been installed correctly causing it to overheat and burn.
well these are just some possibilities i can think of.
Good luck!
-f1