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?