970A-UD3P no display

[ajasper]

GA-970A-UD3P rev 1.0
AMD Phenom II X6 1100T 3.3GHz
Corsair Vengeance 8GB 1866MHz 1.5v ver 3.24
Corsair CX750M power supply
Windows 7

PC has been very reliable for 2 years.  Yesterday I powered it up and could smell burning dust.  I couldn't get anything on the display.

* HDD is spinning up.
* All fans are coming on.
* I replaced the HDMI cable.
* I tried it with the VGA cable.
* I tried it on a different display incase the monitor was broken.
* Reseated the memory SIMMs.
* The keyboard LEDs don't light up.
* The LED light in the  mouse doesn't light apart from briefly at initial power.
* I have tried a different graphics card.
* I dusted everything.

* Next step is replacing the conductive paste as it looks very dry and no longer evenly covering the CPU and water cooled fan.  Hopefully CPU isn't damaged.

* I have a spare PSU but as the fans are working I'm leaving that till last.

* I've cleaned down the CPU and heat sink contacts and applied new thermal compound.
* I've installed a motherboard speaker.

I can't hear any beeps from the speaker on power up.   The motherboard LED is lighting up.

Next thing is PSU.  I have a spare in the loft.

Part of me thinks the burning smell spells bad news for the CPU as the thermal paste was all dried out.  I've never seen that before.




Thank you

Andrew

[shadowsports]

To be thorough try with a different PSU as you mention.  You can also remove additional components for troubleshooting failure to POST.

If things continue to fail.  I'm more inclined to say BIOS issue or component failure on the board if testing with another PSU doesn't resolve.

Thermal paste doesn't remain tacky and pliable its entire life.  In fact, it will eventually become dry and crumbly.  However, it is still able to perform its job by providing a conductive interface between the top of the CPU and heatsink. 

Its effectiveness is diminished if removed or disturbed, but otherwise it will work for many, many years.  Let us know what you find    Good luck!   

[ajasper]

Thank you for your suggestion.  I will try with another PSU, then CPU then motherboard.

The burning smell linked with one of the two CPU cooler screws being a bit loose and lots of dust in the CPU fan is leading me to think CPU damage.  Don't know how the screw became loose as I've not moved it.

I should have cleaned it more often.  Too busy.

[ajasper]

I've tested a spare PSU.  Nothing changed.

I checked the old PSU with a digital multi meter.  It looks fine.

I have checked the motherboard for visible damage to capacitors.  Nothing is blown and no signs of burning.

CPU or Motherboard.  I know which is easiest to physically replace...both are about the same price.  Hmm.... if only I had a spare CPU.

[shadowsports]

Have you tried to invoke booting from the back up BIOS?   

[ajasper]

From reading another forum it looks like I need to press Alt+F12 to copy the back-up bios over.

I will try that tonight.

Thank you for the suggestions.

Andrew

[shadowsports]

That's True, but you need to have a machine that will POST to have that option.  Start by trying to invoke the back up BIOS 

[ajasper]

Alt-F12 didn't work.  The keyboard just doesn't respond at all apart from the initial flash of light when I switch the machine on.

New PSU and CPU.  Still no joy.  It's not posting or beeping.

I think it must be the motherboard.  Even though I couldn't see a popped capacitor I think it must have got damaged through overheating/dust.  I'll try the graphics again before I go there.

[ajasper]

That's True, but you need to have a machine that will POST to have that option.  Start by trying to invoke the back up BIOS 

Ok.  Just re-read your post and found a page which helps with invoking the backup bios:
http://www.overclockers.com/forums/showthread.php/697533-GUIDE-Forcing-backup-BIOS-on-Gigabyte-motherboards?s=5e64cf49bfbcbdc3ab06d6ad731a0e51

I'll try this.

[ajasper]

I replaced the motherboard Saturday night.  Everything is working now.

I couldn't see any blown capacitors on the old motherboard.  When I took the CPU out the pin side looked discoloured - dark golden brown rather than the nice bright shiny golden colour of a new one.  Also, the ZIF looked a bit discoloured.  But then there is a lot of heat around that area anyway.  Given that one of the two bolts on the heat sink was loose I think that's what caused the problem.   

The good news is I've learnt how to invoke the back up bios.  Also, I've left the internal speaker on the board.

Thank you for your help.

 :-)