[SonnyProduction]

I have:

Gateway GT5408
Win 7
Intel Core 2 Duo E4300
320 GB SATA II HDD
2048 MB PC2-420 DDR2 533 MHZ ULTRADDR2

PSU ATX-300-12E REV DR

I had to remove my PSU to replace my DVD... Now the computer doesn't come on. The fans turn and immediately stop when power is plugged in, and the green MOB light (CR3J1) remains on. The power button does nothing. When I unplug it, after a few seconds the light goes off with a faint power down beep from the PSU. Everything was working fine before.

Please help! Thanks!!

 

[Tyree]

Apparently you did not get all the power connections replaced properly/securely.
Or the DVD is causing an issue. Try unplugging the new DVD to be certain.
If no change, check all the power connectors.
The 20+4 pin & 4 pin CPU power to the Mobo are the two required for the PC to boot and run.

 

[SonnyProduction]

I tried disc and still same thing. Reconnect Dane issue. I don't see a 24 prong? Could you describe it? .

 

[Tyree]

The 20+4 pin connection is the largest bundle of wires on the PSU. Better PSU's usually have a sleeve on the bundle and cheaper PSU's usually have the wires zip tied together.