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VGA Post light - possible bad motherboard?

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December 5, 2010 6:37:12 PM

Built a new machine a few weeks ago - specs are as follows:

P7P5D-E motherboard,
2x 4g Corsair XMS3 1600mhz ddr3 ram
800gb WD 7200rpm hdd
optical drive
Corsair TX750W psu
cooler master CPU heatsink
i5 760 cpu, stock (no O/C)
XFX Radeon HD 6870 1gb GPU

Completed the build, installed windows 7, everything has run without a hiccup for a few weeks now.

Today, I went to boot up the machine and got no image on my monitor (output is via DVI). I took off the side of the case to see what was going on, and lo and behold the boot sequence was stopping at the POST LED for VGA, beside the graphics card. It tests the RAM first, and that POST passes, then it halts at the graphics card. My first thought was that my GPU was a lemon, but I took it out and tested it in another machine, and it worked fine. I then took a working GPU from another desktop and put it in the original machine and had different results.

This time, with the other GPU in place, the system passed the VGA post LED, and the Boot Device post, sent power to the USB devices (mouse and keyboard), and acted as though it was booting up.. but still send no graphic signal to my monitor. Keep in mind, I know that the card is working.

I have tried both PCIE slots in the mobo with both GPU's, which I know are functioning cards. I have reset the CMOS with the jumpers, as well as removed/re-inserted the mobo battery. Still getting stopped at VGA POST every boot. One or two boot ups have gotten past that, but the same results as before occur - no graphics output at all.

Nothing changed between yesterday (when the machine worked fine) and today. No temperature variation, no change in config, no update to the BIOS.

I am thoroughly stumped! Any ideas would be greatly appreciated. :) 

Thanks!
Adam
a c 207 Ĉ ASUS
a c 717 V Motherboard
December 5, 2010 7:12:09 PM

Welcome to Tom's Forums! :) 

Here's some tests Simple to Hard.

Simple:
I assume you meant ASUS P7P55D-E, and I assume that you connected the PCI-E Cable from the PSU to the GPU. Also, verify that HD 6870 is properly seated in the blue PCIe slot. If there's a poor connection then yes you can have a similar problem. Also, I would recommend using Isopropyl alcohol -> dampen the GPU connections insert/remove + clean and repeat once more; allow the alcohol ~10 minutes to dry.

Grounding:
Unscrew the stand-off MOBO screws and pull from the I/O Shield use a towel to support MOBO and start. Remove any other PCIe or USB devices, and unplug all but the Primary HDD. This is a simplified method of breadboarding to rule-out Shorting or Grounding problems.

Power:
Firtst, try another PCIe plug from the Corsair. Failure -> A 'simplified' PSU test - since it seems that you have another PC and if you don't want to pull its' PSU then park it close and try its PCIe plug.

CPU:
Unfortunately, the P55 is the #1 MOBO for bent CPU pins and if the above fails then pull the CPU and look for bent pins.
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December 5, 2010 8:20:08 PM

jaquith said:
Welcome to Tom's Forums! :) 

Here's some tests Simple to Hard.

Simple:
I assume you meant ASUS P7P55D-E, and I assume that you connected the PCI-E Cable from the PSU to the GPU. Also, verify that HD 6870 is properly seated in the blue PCIe slot. If there's a poor connection then yes you can have a similar problem. Also, I would recommend using Isopropyl alcohol -> dampen the GPU connections insert/remove + clean and repeat once more; allow the alcohol ~10 minutes to dry.

Grounding:
Unscrew the stand-off MOBO screws and pull from the I/O Shield use a towel to support MOBO and start. Remove any other PCIe or USB devices, and unplug all but the Primary HDD. This is a simplified method of breadboarding to rule-out Shorting or Grounding problems.

Power:
Firtst, try another PCIe plug from the Corsair. Failure -> A 'simplified' PSU test - since it seems that you have another PC and if you don't want to pull its' PSU then park it close and try its PCIe plug.

CPU:
Unfortunately, the P55 is the #1 MOBO for bent CPU pins and if the above fails then pull the CPU and look for bent pins.


I did pull the CPU and check early on. However, POST isn't stopping at CPU, I see no bent pins, and I don't see how it would function fine for 3+ weeks with a bent pen then suddenly stop working.

I tested the PSU as stated and tried the minimal-device boot without the standoff screws. Cleaned the GPU connectors, still no dice. Again, both cards work fine in another desktop and this GPU worked fine yesterday.

Is there any sort of jumper setting that I can set to reset motherboard settings for the GPU, besides the obvious CMOS reset?

:( 
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Related resources
a c 207 Ĉ ASUS
a c 717 V Motherboard
December 5, 2010 9:59:44 PM

No, there's no magical jumps for to help the GPU.

No, besides the stand-off there the I/O shield; both the MOBO and GPU need to be 'dangling.'

Next, you mentioned another PC - if it too has DDR3 RAM then - pull the {XMS3} and try 1 stick or at the very least try 1 stick of the {XMS3} -> failure try the other stick.

Before 30 days - I rule-out nothing and a poorly connected pin can work fine one day and poof the next. You can Post and run the GPU all day but miss RAM; it depends upon 'what' pin is poorly connected.

As I said, all of the above are possible, that leaves the CPU or MOBO. I assume it's a good idea to check before assuming. ;) 

Keep in mind in order for the GPU to run 'fine and dandy' the dependencies: CPU, MOBO, Power, RAM and obviously the GPU {plus proper installation} must too be OK; all play a role and all can cause the LED to turn-on. Heck I've seen a shorted mouse cause post failure.

---

Keep in mind while a I assume a bad MOBO or CPU I am trying to systematically rule-out everything else prior to suggesting an RMA.
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April 11, 2014 1:36:57 AM

I have a similar problem. I enabled the ErP setting in the BIOS because I was annoyed that m mouse and keyboard lights would be lit up after pc is off but when i saved and reset, it got stuck at the POST screen. I turned off PSU and rebooted but now it doesnt send a signal to monitor. The POST led stops at the VGA. I have a ASUS Z87-C motherboard.

I have also posted a thread about this.
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April 11, 2014 2:47:08 PM

I have found a solution for my problem. Try clearing the CMOS/RTC RAM on the motherboard. It's a jumper.
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!