Question : Problem: My Dell refuses to power on

I have Dell Dimesion 5100 which one day stopped turning on. To troubleshoot the issue I have tried quite a few things such as disconnecting all extra cards, memory etc without any difference.

What I did next was to disconnect the main power from the motherboard and then "jump start" the PSU by connecting the green and black wires. This made the power fan turn on so the PSU seems to be fine. Next I connected everything together, jump started the power by both shorting the green wire and also pressing the power button I can hear that HD etc turn on but there is no "beep" nor "video". The computer stays powered on, with the power button showing a yellow light, and does respond to holding in the powerbutton for turning off.

Any suggestions what else to test or try before I order a new mother board?

Thanks in advance...

Answer : Problem: My Dell refuses to power on

I ordered and put in a new motherboard, as if by magic, I'm writing this reply from the previously broken computer.  

Thanks for the suggestions...

Best regards....