So my old Nvidia 8600GT broke and i got myself a Sapphire ATI Radeon HD 5770, And ever since when i have been trying to play COD 4 my PC will shut down say 10-15 minutes into the game, i am still able to hears fans and see lights coming from my PC but. Strangely it seems to be able to last longer in Company of Heroes which i would assume uses up a lot more juice than COD 4.
My PC is custom built and i asked my dad's friend (the guy who built it) and he said it's probably the PSU and i forgot how much watts he told me it was and when i open up my case i see nothing on my PSU except one small sticker and i have absolutely no idea what it means, it doesn't tell me watts, volts, amps or anything. It's basically just a bunch of boxes with a tick in one of them.
Now heres something interesting, A couple of times when i tried to turn on my PC right after it crashes it gives me a screen with some info of my PC (basically just memory, hardrives, usb devices etc) and at the very bottom of it it says CPU Over Temperature Error Press F1 to continue.
Also i just cleaned quite a bit of dust off my fans and i still get this problem.
CPU overtemp error is something you have to fix, it is shutting down your computer. Did you clean the CPU cooler thoroughly? If so it is time to reapply thermal paste. Take the cooler off clean the old paste off and reapply new paste.