The possibilities for cause of failure appear to be failed video adapter, failed
motherboard in general, failed CPU (unlikely), failed power supply (maybe
unlikely) and failure of some other device.

There are several approaches here.
One is to install an old PCI video card and see what happens.
Another is to use a POST card, a special PCI used to diagnose problems with a
system booting up.
Or you can try another known good power supply because part of the existing
power supply could have failed. You can use any ATX12v power supply.

To isolate failure of another device, unplug floppy, hard drive, CD/DVD drives,
and see if the system will at least boot up to the BIOS screen. If it does,
plug one device at a time. Make sure you unplug the wall power every time you
put your hands inside the chassis.

If the floppy diskette makes its grinding noise a few seconds after you turn on
the computer, my bet is on a failed onboard video adapter. So I would start
with an old PCI video card... Ben Myers

On Wed, 12 Dec 2007 03:07:15 GMT, "debm" u39818@uwe wrote:

my daughter has a compaq presario s4020wm system.it boots up to a black
screen,the green light comes on,the dvd rom tries to boot,the floppy also
tries to boot,we know the monitor works because we tried it on another system,
how can we tell if the onboard video adapter is bad?and what else can i do to
get it to boot to the operating system,also there are no beeps to confirm
what is wrong.help....