CPU turns on then off immediately

[vivekgk]

I'm trying to fix a computer for my dad. It's an AMD 7750 processor on Asus M3A78-EM mainboard, with 2 sticks of 2GB DDR2. It wasn't starting up.

When I push the power button, the CPU fan starts, and stops immediately. The LED on the mainboard is glowing when I connect the power cord. There are no beeps heard, the whole thing just turns off almost immediately.

I tried switching out the PSU, RAM, and even the case, and disconnected everything except one RAM (tried both).

Any ideas on what it could be?

 

[tigerg]

Remove all parts down to the very most basic, a CPU (properly installed and with a cooler), 1 stick of RAM, and the PSU. Try to boot. If it doesn't switch out the RAM and/or try different slots.

Hopefully your computer will POST and you get get to the BIOS.

Does it post when you try these combinations? If not, you have bad RAM, a bad PSU, a bad CPU, or a bad motherboard. You will need to swap these components out to isolate which one is faulty.

 

[vivekgk]

Remove all parts down to the very most basic, a CPU (properly installed and with a cooler), 1 stick of RAM, and the PSU. Try to boot. If it doesn't switch out the RAM and/or try different slots.

Hopefully your computer will POST and you get get to the BIOS.

Does it post when you try these combinations? If not, you have bad RAM, a bad PSU, a bad CPU, or a bad motherboard. You will need to swap these components out to isolate which one is faulty.

I've already tried disconnecting everything except the power switch and the RAM. It turns on then off immediately. I'll try to get a new DDR2 from somewhere and check if that works. Thanks.

 

[tigerg]

Remove all parts down to the very most basic, a CPU (properly installed and with a cooler), 1 stick of RAM, and the PSU. Try to boot. If it doesn't switch out the RAM and/or try different slots.

Hopefully your computer will POST and you get get to the BIOS.

Does it post when you try these combinations? If not, you have bad RAM, a bad PSU, a bad CPU, or a bad motherboard. You will need to swap these components out to isolate which one is faulty.

I've already tried disconnecting everything except the power switch and the RAM. It turns on then off immediately. I'll try to get a new DDR2 from somewhere and check if that works. Thanks.

You need a CPU to power up.