Calling on all PC diagnosticians! Please help.

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yeti

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[SOLVED] PC suddenly won't post (Asus z77/MSI 6950)

Hi Guys,

I recently purchased
- i7 3770k
- Asus P8Z77V
- 4 x 8Gb Corsair Doms 1.5v CL9
- Corsair H80

which I added to my
- Corsair AX750
- MSI 6950 2Gb

The setup worked for the first few days but seemingly out of the blue stopped posting on Friday evening (Was happily working on Thursday evening).

I removed all components from the system and added them one by one, with the PC failing to post with the GFX card inserted. The motherboard actually includes LEDs on the various subsystems to show you were it stopped posting and ideally where the issue is - and this was the LED above the PCI-e slot.

I tested a second GPU (6850) in the same slot with all the other components and the PC boots as expected. I then tested my 6950 in a friends PC which also surprisingly booted. I was fairly certain that it was PSU/GFX but I am now not sure how else to test the PC to identify the faulty component.

Any ideas?
Click to expand...

Resolution:
Bios update. All of a sudden. No CUD related additions.
Download the latest[0] Asus P8Z77V bios firmware update here (under the BIOS sub-heading).

[0] At the time of writing the most recent update was dated 18/10/2012
(Edit: just noticed the correlation between the date the firmware was released and when my PC stopped posting)
 
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There were other reasons to suspect the PSU, as I was getting sporadic errors with all my sata devices connected. For example, it failed to boot once with my DVD connected. I am not confident in this result however, as I do not recall exactly what was connected at the time of failure. We have had one/two power failures recently (the PC was powered down but connected) but as far as I can remember it did post after them.
 
I had the weirdest kak when my PSU went faulty. Like a sound card that played noise out of two channels, the rest worked perfectly.
 
when u get strange stuff like this happening its usually the PSU that or faulty MB but seems
more like a PSU.
 
I also tested the system on a different PSU without the GFX card (I don't have a spare PSU that can power it) and it booted as expected.
 
Get the PSU tested you have done so much other testing to prove it is working that the only component not tested is the PSU.
Maybe a trip to you local friendly computer supplier (Not one of the chain stores) would help get the problem resolved.

Regards

Tim
 
How many Pci-e power connectors do you have on your PSU? If you have more than two than try the alternate pci-e connectors just to rule out the fact that the pci power cords/connectors might be faulty, or possibly the module inside the PSU that delivers pci-e power could be faulty . Seeing that you have an AX750 I'm sure you have extra pci e cables try the spare cables to my knowledge the ax750 comes with 4 6+2 pin pci power cables. you were only using two that u needed for your gpu right? so u must have two spare cables since this is a modular psu just give the spare cables a shot. sometimes there might be a short within the cable due to wear and tear
 
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avid-dreamer said:
How many Pci-e power connectors do you have on your PSU? If you have more than two than try the alternate pci-e connectors just to rule out the fact that the pci power cords/connectors might be faulty, or possibly the module inside the PSU that delivers pci-e power could be faulty . Seeing that you have an AX750 I'm sure you have extra pci e cables try the spare cables to my knowledge the ax750 comes with 4 6+2 pin pci power cables. you were only using two that u needed for your gpu right? so u must have two spare cables since this is a modular psu just give the spare cables a shot. sometimes there might be a short within the cable due to wear and tear
Click to expand...

Thanks for the advise, ill give that a try!
 
Took my AX850 box (sans cables) and HD6970 to yeti's crib. After testing everything, including the cables and separate PCI-E power port, it turned out that a simple motherboard BIOS update solved the problem. Now hid HD6950 works. Really odd, perhaps related to a Windows update? :confused:

All good now.
 
Makes sense . Alot of newer motherboards have limited pci-e rom compatibility when launched, then later on they release bios versions with better pci-e rom compatibilty. I noticed recently on the changelog for my MSI z77 bios they mentioned something about gpu compatibility issues in relation to the pci rom embedded in the boards pci-e controller. So it seems to be a common issue :confused: but solutions for problems like these dont just pop up in your head, especially when troubleshooting matters like these is such an annoying process. It was probably just a corrupted pci rom. Basically a PCI rom is the code executed during bios initialization to initialize your pci/pci-e devices, A corrupted PCI rom just means that your pci-e device (eg. certain gpu) wont initilaize and in turn your PC wont post. Now this doesnt mean that all gpu's or pci-e devices will be affected but IMO it could fail to initialize certain devices in this case Yeti's 6950.
 
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avid-dreamer said:
Makes sense . Alot of newer motherboards have limited pci-e rom compatibility when launched, then later on they release bios versions with better pci-e rom compatibilty. I noticed recently on the changelog for my MSI z77 bios they mentioned something about gpu compatibility issues in relation to the pci rom embedded in the boards pci-e controller. So it seems to be a common issue :confused: but solutions for problems like these dont just pop up in your head, especially when troubleshooting matters like these is such an annoying process.
Click to expand...

It certainly seemed to be a compatibility fix - but how then was it working before the fact? Suspect.
 
yeti said:
It certainly seemed to be a compatibility fix - but how then was it working before the fact? Suspect.
Click to expand...

Like I said.... PCI-e Rom corruption. Yes corruption is not only limited to our government :D. Bios roms are limited in the amount of code they can run so rom corruption is possible. A quick bios update refreshes/updates the rom code and "Hey presto" its fixed.
 
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