My Dell Dimension 4550 won't power up. New P/S, power cord, etc. doesn't help.?

[gbsdirect]

The system's fan was very loud so I put in a new power supply and then everything booted up fine. Unfortunately, that didn't solve the problem. It was the Motherboard fan making all the noise.

So, I put the old power supply back in and now the system doesn't power up at all. I checked all connections & I replaced the power cord and tried a different electrical outlet.

I even put the new P/S back in and nothing changed. It still doesn't power up. It's dead!

Any suggestions?

 

[kimsland]

It was the Motherboard fan making all the noise

Do you mean the CPU fan ?
If so then I wonder if the CPU has been cooked

I would start by dispersing all internal voltage.
Detach the power cord
Press the power button in for 20 seconds
Re=attach the power cord
Try again

If it didn't fix then remove all addons, usb devices really anything attached (except screen and keyboard and power cord)
And try again

If it didn't fix then, confirm all internal connections are secure (even detach the dvd drive{s}

If it didn't fix then try disconnecting all fans (what !) for about 10 secs (turning on) I once had a fan of all things, that stopped my computer from turning on (unbelievable, I know)

Lastly, check the CPU for heat damage !