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Blank Screen Doesnt Boot

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November 17, 2012 6:13:31 PM

hi all,

I have a computer with the following spec

Asus p4c800 e deluxe
2 x 1gb cosair xms pc3200
2 x 250gb sata hdd
Radeon 9250 graphics
400w psu


Ive used my computer for a long time with no issues, i was using it one day, just typing and my computer froze, i restarted it from the tower and got a blank screen.

From a cold start all fans are working, light on the mobo, hdds, cd drives etc all working. The screen is displaying nothing. No beeps (computer didnt ever beep even when it was working), no flashing cursor, just a blank black screen.

Ive switched montiors, changed graphics card, changed memory to one stick using new memory, each vairable done and tested each time...still get nothing on the screen.

Ive taken out the mobo battery, and also changed it for a new one, still done nothing.

the HDDs are spinning

Ive tested the PSU manually and is all working fine.


Do you know whats going on with my computer?

Thanks.

November 17, 2012 6:25:04 PM

Hi,
If starting with only CPU and CPU fan installed do you get the error beeps?
November 18, 2012 4:22:14 PM

Hi, thanks for the reply,

My computer never used to beep even when it was working correctly (for the last 10 years). So now there are no beeps,

i have started the computer as you stated and still there is nothing on the screen, its completly blank, no beeps.
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November 18, 2012 5:09:16 PM

It means it doesn't have a case speaker connected.
Can you connect one?
November 18, 2012 7:49:44 PM

Hi, yes you were right, the case speaker wasnt connected to the mobo

Ive connected it up now and there are no beeps...what does this mean?

November 18, 2012 7:57:24 PM

Start with ony CPU and CPU fan connected (no RAMs and graphics card). You should get one long two short beeps.
If no beeps and the case speaker does work and is correctly connected to the board's system panel connector then it's either a motherboard or a CPU issue.
November 23, 2012 5:17:48 PM

alexoiu said:
Start with ony CPU and CPU fan connected (no RAMs and graphics card). You should get one long two short beeps.
If no beeps and the case speaker does work and is correctly connected to the board's system panel connector then it's either a motherboard or a CPU issue.



Thanks for your reply, sorry for not replying earlier

I have changed the motherboard, and now im getting one beep, the computer starts up(blank screen), beeps (short beep) then shuts down on its own one second after the beep.

there is nothing displayed on the screen

I have put in 4 different sticks of memory, checked connections etc. and still just booting, beeping, then shutting down

one thing is, when i switch on the psu from the back, the computer boots on its own, without me having to use the case button...why is this?

November 23, 2012 5:35:14 PM

It might be a wrong connection.
Disconnect the power and the reset switches from the system panel connector. See if still the same. Testing the board outside the case would also help (ruling out a shorting issue).
November 23, 2012 6:03:58 PM

alexoiu said:
It might be a wrong connection.
Disconnect the power and the reset switches from the system panel connector. See if still the same. Testing the board outside the case would also help (ruling out a shorting issue).



Thanks for your reply.

what do you mean by "reset switches from the system panel connector"?

November 23, 2012 6:15:24 PM

The case's reset and power buttons connect through wires to the motherboard. They might not be correctly connected.
November 23, 2012 8:51:55 PM

alexoiu said:
The case's reset and power buttons connect through wires to the motherboard. They might not be correctly connected.




PWR-LED (My case doesnt have this wire)
ATX-SW (Connected the Power on/off wire to this)
HD-LED (I have not connected this)
RESET (Connected to the reset wire)
SPEAKER (Connected the speaker wire)

I have wired as pictured, according to the lines on the motherboard.





November 23, 2012 9:07:18 PM

Here's what I would try: with the board outside the case, start it with only CPU and CPU fan installed. See if the board still starts when powering on the PSU (without pressing the case power button) and if you get the error beeps signalling no RAMs installed - 1 long, 2 short.
November 24, 2012 12:24:44 PM

alexoiu said:
Here's what I would try: with the board outside the case, start it with only CPU and CPU fan installed. See if the board still starts when powering on the PSU (without pressing the case power button) and if you get the error beeps signalling no RAMs installed - 1 long, 2 short.



Again thanks for your continued help....i think weve cracked it!

I took out the power and restart switch wires from the mobo, and switched on the PSU, nothing happened, my mobo has a on/off and a restart switch on the mobo (fist time ive seen this) i pressed the power button and it worked!! so there must be something wrong with my front panel power wire? how can i get around this?

also all the above was done whilst my mobo was still in the case.

now, for some reason its not booting from my SATA hard drive, ive disable IDE HDD controller from bios..and also enabled the SATA controller, it boots from Floppy fist, then hard drive, but doesnt pickup the SATA hard drive....any ideas?

I still have all my info on the SATA drive from before my mobo got messed up, so it has windows already on it and all my data etc.

Thanks again for your amazing assistance.
November 24, 2012 5:03:04 PM

No problem. So, it seems to be a problem with the chassis' switches and with the SATA hard drive. Firstly the SATA issue. The board has two SATA ports. Connect the HDD to the oher one ad see if still the same. Can you test the HDD in a different PC?
November 25, 2012 11:32:34 AM

alexoiu said:
No problem. So, it seems to be a problem with the chassis' switches and with the SATA hard drive. Firstly the SATA issue. The board has two SATA ports. Connect the HDD to the oher one ad see if still the same. Can you test the HDD in a different PC?


Thanks so much...it worked!!! :) 

I plugged the SATA into the other socket and also set hard drives to auto and it picked up the SATA with no problems. It was first searching for IDE HDD.

Now for the switches...is there anyway of sorting that out? I dont want to be opening my computer everytime i want to switch the computer on with the mobo switch.
November 25, 2012 2:44:50 PM

Here's the manual for the board:
http://dlcdnet.asus.com/pub/ASUS/mb/sock478/P4C800E-DX/...
At page 2-33 it's the system panel connector.
With the power supply off, connect firstly the power switch only (2 wires: Pwr and Ground). Turn on the power supply and try starting the board from the case power switch.
But the connector in the picture you've posted looks different that the pinout in the manual. Or am I wrong?
Even in this picture the connector looks different: http://www.tomshw.it/guides/hardware/motherboard/200407...
November 25, 2012 8:28:13 PM

alexoiu said:
Here's the manual for the board:
http://dlcdnet.asus.com/pub/ASUS/mb/sock478/P4C800E-DX/...
At page 2-33 it's the system panel connector.
With the power supply off, connect firstly the power switch only (2 wires: Pwr and Ground). Turn on the power supply and try starting the board from the case power switch.
But the connector in the picture you've posted looks different that the pinout in the manual. Or am I wrong?
Even in this picture the connector looks different: http://www.tomshw.it/guides/hardware/motherboard/200407...



Thanks for the reply.

Sorry i didnt telll you, my replacement board was not a P4c800 e-deluxe (i couldnt find one). I replaced it with a DFI LanParty pro875b
November 26, 2012 9:26:36 PM

alexoiu said:
I see.
Here's the manual: http://us.dfi.com.tw/Upload/Manual/CM/lanparty%20pro875... The connector is at page 17



that was unsuccessful I'm afraid. The computer still starts up on its own then the power wire is plugged up, and then I hear a beep, and then it shuts off on its own. I tried it with the connector turned both ways.
November 27, 2012 10:02:27 AM

With the board's header not connected to any case switches/leds, try shorting for a short time with a screwdriver the 2 pins corresponding to the power switch. My guess is that the case switch is broken and after being pressed and released it keeps the two wires connected.
November 27, 2012 11:33:17 AM

alexoiu said:
With the board's header not connected to any case switches/leds, try shorting for a short time with a screwdriver the 2 pins corresponding to the power switch. My guess is that the case switch is broken and after being pressed and released it keeps the two wires connected.



Thats totally what i was thinking too - I would need to try and find a replacement switch.
November 27, 2012 1:37:00 PM

When pressing the switch it actually connects the 2 pins from the motherboard's header. That's why I suggested shorting the 2 pins with a screwdriver. Just to make sure it's a switch issue.
!