Re: MSI Geforce GTX260 SP 216 Heat jumping
I would reseat the heatsink again just to be on the safe side, and if it's still doing it consider replacing the card.
As fast as your temps are rising either the fan or the card is defective. I would lean towards the fan. Does the fan spin up right away when you start the computer? If not, even a 2 or 3 second delay with a 3d app running is enough to cause you trouble.