power but no boot no codes or video

friend has 4 year old hp desktop running win xp, power supply works, fan on cpu works, cd-rom has power to open and close, harddrive light is on, on the power button, there is no video the stand by light is on on monitor there are no beep codes. on harddrive sounds. so would it be safe to say that the mobo is shot?
i hooked up another power supply so know it is not that.

 

Does this pc have onboard video? Have you tried another video card? I would clear cmos and try again, unplug power supply, take mb-battery out for a few minutes and see if it will boot.

 

same problem a while back and it was the mobo. i had all fans and lights power up but no hdd spinning or video output to the screen. no post beeps either. fixed it by replacing the mobo. one bad thing about replacing mobos in systems that are prebuilt (Sony, HP, Dell etc) are that they usually use some whacky form factor for their motherboards and i dont know if they make aftermarket mobos that will fit. I had to resort to buying a new case which im now glad i did.

 

Couldn't tell from this typo...did you mean to say that there are NO hard drive sounds, or that there ARE hard drive sounds when the comp is on!?!?

If you are saying that the hard drive IS making noise, then I would say from experience that I would start by suspecting the video card is shot!! However, if the motherboard uses onboard video, and the video is the issue, then ofcourse replacing the motherboard would resolve the issue. If it is onboard video, then does it also have an AGP slot, if so you could try putting an AGP video card in and see if it works, but that usually involves getting into the BIOS and disabling the onboard video, which can be a trick since you don't have any video, but you might get lucky and it will automatically boot to a new AGP or PCI video card. Had this exact scenario happen to me on a friends Dell with onboard video and the only way to fix it was to replace it with a replacement board from Dell!!

If you say your ARE NOT getting hard drive sound when the system boots, then I would say it is the motherboard!!

If you do get a replacement motherboard...then log onto the online live 24/7 chat with HP and check out from them if you will have to order a proprietary replacement board or if an aftermarket board will fit!!!!

Roger

 

Thanks, and yes it was a typo, i did mean no sounds. i will try the battery thing.

 

And make sure all the power connectors from the PSU to the individual drives (all the connectors for that matter!!)are plugged in good.

Roger