Computer Boots but no display

Hello, im really hoping somebody can help me with this..

My PC powers up but I get no display. Ive tried resetting the bios using the jumpers but to no avail.
The fans work and the HDD's work but no power to my dvd rom? and no lights to the front of the machine.

I was working on it one day and the restarted the machine and it started to ask me for all the basic drivers again e.g HD Compliant mouse, keyboard.....
I did this and it worked ok restarted again and had 'Checksum error - defaults loaded' . I thought this was a dying battery so i changed it and nothing. I even bought a new bios chip but nothing.

Ive tried the video card in another machine and it works fine, ive used other monitors and nothing.

Some people have said it may be a PSU problem, could this be the case??

Any help would be much appreciated. Many Thanks in advance.