I think I already know the answer, but I'll ask anyway.

I have a P35 board that started freezing up, then started rebooting randomly.

Ran memtest, errors even at stock with two different kits. Tested cpu and both kits on a different board, no problems.

I'm guessing Northbridge/memory controller is cooked.

As far as I'm concerned, I've got nothing to lose but, do you think baking the board (or maybe a heat gun on the northbridge) will help?