GA-P35-DS3R overheat damage?

Hi guys, need your assessment for this one. I built a new rig two weeks ako, with the following specs:

Intel C2D e6750
GA-P35-DS3R
2gb Ocz Platinum rev2 PC6400
8800 Ultra
Corsair HX620W PSU

System ran fine OC'd to 3.0GHz but was unstable at 3.4GHz so i decided to cool the northbridge.
I was connecting a fan to the NB heatsink when i accidentally lifted the heatsink off a little to the side.

Anyway, after a few hours of gaming my whole system suddenly goes down with this whistle-like sound. After this it would post all right but would shut down after around 3-10 seconds. I figured it was an overheating problem when i left it to cool after an hour and it would run fine again. I'm pretty sure its not the CPU since i get 55C under load with CoreTemp and Speedfan. I can't tell how hot the Northbridge is getting but the heatsink is really hot to the touch.

I decided to reseat the NB heatsink last night with AS5, and when i did, i noticed the the NB chip itself had this suspicious looking bulge right next to the die (will post pics when i have the time). The worse part is, my system won't go past post anymore, even when left to cool overnight.

Now i have a few questions:
1. Is there possibly anything else besides the mobo that could be causing this? I was thinking PSU might be at fault, but the voltages seem to be ok when it was under windows.
2. Has my mobo suffered permanent damage? If so i'll try to RMA the board.

I've unplugged pretty much everything unnecessary from the pc and its running fine. I might have to look into a bigger PSU or replacing my current one. Thanks a lot nuke!

Anyway, might as well add in the pic of the NB: