System turns itself off

[sbfjones]

i have a computer that crashed. i changed the power supply. it started. i was making sure that the system was OK, when the system turned off. it would not power up again. i changed the CPU next. the computer still will not power up. if unplug the computer, after a little bit plug it back in an push the start button the computer will start then turn off. the longer the copmuter is unplugged the longer it will run when it is powered up.

[Hopester Doofus]

Your processor may be overheating. With the cover off, turn on the computer and check the fan above the processor to see if it's spinning.  If it isn't, that's your culprit.

[sbfjones]

thank you for your help. the cpu fan is turning.

[patio]

What do you mean when you say you changed the CPU ? ?
Did you remember to use Thermal Compound in doing this ? ?
What brand/wattage of PSU did you swap in there and was it new or used ? ?

More Details...

[sbfjones]

When i changed the CPU i put a back up CPU that i had that is a good one that works with the mother board. an yes i put new thermal grease on the CPU. the power supply is a used on that i have and it has the same spec. an watts that the bad one had.