Black screen, no boot, no beep sounds

[Stanka1]

Hello. I have a problem with my HP Compaq dc7900 Small Form Factor PC. When I turn it on, it does not boot, but only power LED lights up green (no red LED or beeps) and after a few seconds the fans starts to max speed which makes the desktop noisy. What can be the issue ?

[Bill_To]

Hi

Your PC supports Windows XP. Your PC has been around for quite a while. It may have hit end of life.

I would first (when the PC is off and disconnected from AC power) reset CMOS by removing the CR2032 MB battery. Let the PC sit for a while. Install a new MB battery. Check all wiring connections to the MB. Reseat connected components.

Then look at the power supply. Trying a different PSU would be quick and fairly inexpensive.

Reduce to a minimum configuration (one stick of RAM and CPU). Try one stick of factory RAM in each memory socket. Try compatible replacement RAM in each memory socket.

The symptoms suggest a failing component down to the MB if the PSU is okay. The BIOS could also be corrupted.

You would have to swap in other, known good replacement components to find the bad part.