4870x2 with arctic cooling accelero xtreme, freezing on games

I installed this cooler on my 4870x2 about a week ago and all was good, idle temps stuck at 33 degrees.. A week later i try running any game, and the monitor loses the signal and the computer locks up. The card isnt overclocked at all either.. Any ideas? XD

edit: I've just noticed the middle red LED lights up when i lose the screen, i cant find what these LED's mean anywhere.

Hardware is as follows:

Asus maximus II formula
Intel q9550
Corsair dominator ddr2
Ati 4870x2 with arctic cooling accelero xtreme
Thermaltake toughpower 750w ps

Thanks in advance =)

I solved the problem and I'll just mention this incase anybody else has any issues. Ccc and rivatuner weren't picking up the 2nd gpu memory and shader temps so I used gpuz which detected the shader and memory idling at 100 degrees.

The problem was the tiny screws connecting the silver plate to the gpu contacts. When I connected the 2 back X brackets which pull the silver contact down which then pulls the 2 gpu contacts down by the tiny screws, 2 of the screws snapped. The 2nd gpu wasn't making full contact and only gpuz would pick up the temp problem.

So be careful when installing this cooler, dont tighten those X plates up too far

idle temps are now 29-33 and load 45-50.