Digimortal

jabujabu, did you ever find any solution for your lag/stuttering issues (ie. fixed with driver updates?). I have similar issues with my ATI 6990m's and no amount of drivers really ever fixed up the issues.

Sound like the switch mode supply in the power brick is having issues, as mentioned by southpole try seeking a replacement.

Where did you purchase the 780's to replace the initial 6990m's from? Would you recommend this to myself with an old M18x R1? I've been plagued by having to use modified drivers to be able to squeeze performance and issues out of modern games, if this would fix this issue I'd love to know.

Nate don't worry too much about the brand of thermal paste, when your machine is at its limits the temperature difference is generally less then a degree. Higher quality brand name pastes only really make a big difference to your idle temperatures. This effect is similar to leaving a car out in the sun on a hot day, even though one may be white and the others black; when both are left till the heat saturates the inside temperature within the car are identical, only the rate at which it takes to get to that maximum temperature changes.