Blank screen

Hi all

I have hp desktop theres power to the fans and graphics card and harddisk but not post and
the screen is black. ive changed the graphics card but still now joy.

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Probably a burned out backlight thingy. Is it under warranty still? Test with an external monitor and see if that works, if os, you will probably need to replace the screen.
If there are no beeps or anything you probably have a bad power supply, motherboard, ram, or CPU (I would troubleshoot in that order).
I would also disconnect all external and internal (hard drives / Printers / CD ROM) devices to see if it posts (I have seen a bad internal hard drive prevent post).
do you see a splash screen at all?  Have you checked to cable to the monitor to make sure its good, also have you checked the monitor on a different computer to see if it works. Pull the memory on the computer to see if it beeps to give us a sign the computer is working
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Raymond PengSystems EngineerCommented:
Does your motherboard have onboard graphics?  If so, try plugging into that first.  When you say it doesn't post - can you provide the number of error beeps and the pattern?  If you don't hear it, you may need onboard speaker to help troubleshoot.  Perhaps try swapping out a good monitor if you're not hearing beeps (could be display issue)

Common reasons for not posting include cpu / memory / mobo / graphics card.

Try posting with only the cpu / 1 stick of ram / motherboard / graphics card (if no onboard) / keyboard.
davy999Author Commented:
1) it not a monitor problem thats been checked and works well

2) Just left one stick of ram.

 3) I have also disconnect all external and internal (hard drives / Printers / CD ROM) devices to see if it posts

4) Changed the cmos battery

still no posts
Raymond PengSystems EngineerCommented:
no error beeps? does it have onboard graphics?

Specs / Brand of motherboard and cpu?
i would say a motherboard if it doesn't beep when you remove all memory
If it's an external graphics card, pull it out, blow out the dust, plug it back in.
If it's an internal card, then like everyone has already said, your motherboard probably bust.
davy999Author Commented:
it has an external card and an internal card have removed external and tried just with
internal no beeps
Raymond PengSystems EngineerCommented:
sounds like your motherboard lacks onboard speakers (should buy one cheaply and hook it up so help diagnose)
and sounds like a motherboard issue if it's not posting but lack of error beeps makes it hard to tell.
Swap out your power supply, if you have not done so.  A malfunctioning power supply can provide enough current to run fans, but not boot the system.  You also need to make sure the 4-wire square plug is connected to the motherboard.
use the minimum setup from my guide for troubleshooting your problem :                  (Short-overview-of-how-to-troubleshoot-bad-hardware-when-a-pc-does-not-post)

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