I was playing COD 4 and my computer would switch off without shutting down. Happened a couple of times until I tried it the next day and the same happened but then my computer wouldn't switch on. I checked the power supply and it was red hot. Took the PSU to a tech shop and they checked it was dead. The guy said that the PSU I had could handle the power but not the current and I needed a better model for my two GPUs.

Got the new PSU and it runs ice cold no matter how long I play COD for.

Happy days.