Stuck in sleep mode won't boot

[Tigger]

I have a pc that I'm trying to work on. I'm wondering if anyone has had this problem and can offer some advice.
What I have is:
HP Pavilion p6142p desktop
Windows Vista Home Premium SP1 64 bit
WD Caviar Blue 640gb hdd
8 gb memory
AMD Phenom x4 64 CPU

The monitor is HP 2009m widescreen (flat screen)

When I try to boot the pc the monitor searches for video signal from VGA and DVI. It shows no signal from either and says monitor going to sleep
Also shows default video input as DVI
Meanwhile when the pc is booting it flashes the 3 lights on the keyboard
no BIOS beeps, nothing on screen except as stated above
and the CPU fan and case fan turns off after about 5 seconds
and the HDD keeps spinning

I have tried booting with a VGA cable, then a DVI cable
I tried a regular flat screen and it showed
(first attempt)
in sleep mode
move your mouse or
press any key on keyboard
(every attempt afterwards lighted blank screen then monitor goes to yellow power button)

I tried removing the cmos battery and replacing it, no luck
I also tried disconnecting the HDD and the optical drive same results
I tried removing all the memory to see if there was any BIOS beeps-none
Any suggestions would be greatly appreciated.
Thanks

 

[ComputerRepairTech]

no BIOS beeps, nothing on screen except as stated above
and the CPU fan and case fan turns off after about 5 seconds
and the HDD keeps spinning

The subject of the thread is really misleading.

CPU fan and case fan turns off after about 5 seconds but HDD keeps spinning. I am going with the assumption that the case fan is plugged into the motherboard? If thats the case I am going with the assumption that something is wrong with the board.

 

[drake3d]

Had this problem with an old Gateway. Check for blown/puffy caps on the board. Sounds like there is power but the caps on MB are not working to keep voltage up properly and it dies.

 

[ThanatosOfOne]

Only the monitor is asleep. That system is not POSTing.

 

[seedubya]

It's not "stuck in sleep mode", the board is kaput. If you want to be sure troubleshoot it properly.

 

[Tech in SC]

I had one just like this a while back. I may be wrong but if my memory serves me correctly it was the PSU... swap it out and see what ya get.

 

[frase]

to the OP have you attempted to reseat hardware - especially the video card to ensure proper clean connection?

 

[Jsch38]

My suggestions

1. Check power supply.
if that is ok then.
2. Remove video card. clean the MB slot with compressed air & reinstall and retry. If not fixed.
3. Try a different video card.
4. If steps still do not fix. Could be MB issue.
Hope this helps.