Ok so my sisters computer kept on overheating and she needed to keep an extra fan blowing on the CPU to keep it running but then that stopped working. I took the CPU fan off and it was extremely dusty so i cleaned it all out and still no luck. I then redone the thermal paste on the CPU fan and it worked. I then turned it off to go do something else and when i came back it was just overheating again. So i took the power block out and cleaned that out because that was also very dusty but still no luck. Also i think i might have put a wire in wrong because it loads up about 7 seconds in and then just cuts out but unlike when it overheats it will restart by itself and keep going to the same place.
Would really appreciate if somebody could try and help on both problems.