[Solved] Persistent VGA Light - Not POSTing

[Cal383]

[Solution]

 

Adding in case someone else is Googling for solutions.

 

It would appear the motherboard must have been shorting to the case. When isolated from the case, it works with all the original components.

 

Hi all,

 

I am chasing down an issue on my son's PC. This issue has been intermittent since building (seriously was rare so he didn't want to do troubleshooting / RMAs) which has become persistent since blowing out the PC with an air compressor. When the issue was intermittent, the PC performed perfectly with no issues other than rarely returning a VGA error and not booting on the first try - usually solved with a reboot. When blowing the PC out I made sure to do all the usual stuff - prevent fans spinning from the air, not getting too close with the air nozzle; I did my own PC the same day in the same manner with no issues. I honestly wondered if the motherboard had micro-cracks in the solder or something that I opened when moving the PC, but troubleshooting demonstrates the motherboard is not the issue.

 

I am hoping that someone might have an out of pocket idea - because at this stage I am honestly a little lost. The only component I haven't isolated in some way is the CPU but I am struggling to reconcile that the CPU could be causing a VGA detection error.

 

The issue:

The VGA light on the motherboard illuminates and the speaker plays one long beep, followed by three short beeps - indicating VGA not detected. This prevents the PC from POSTing.

 

Troubleshooting I have performed:

Swapped PCIe slots - No change.

Swapped GPUs - His GPU worked in my PC, my GPU did not work in his PC.

Cleared CMOS via pins and removing battery - No change.

Tried RAM in various slots - No change.

Tried removing all drives (2x M.2 NVMe) - No change.

Tried booting without anything plugged into PC (e.g. no mouse, keyboard, screen, etc.) - No change.

Tried another motherboard (which included new RAM) - Temporary improvement, in that the issue became intermittent.

Checked voltage to 8-pin connector on GPU - 12v in all the right pins.

 

Troubleshooting I have NOT performed:

Try another CPU - Don't have another LGA1700 to test with.

Try another PSU - My PC does have the same PSU, which I can try if suggested, but I am reasonably confident that it is not the PSU.

 

The system specs:

Intel Core i7 12700F

ASUS TUF Gaming Z690-PLUS Wi-Fi D4

ASUS GeForce RTX 3060 TUF Gaming OC LHR 12GB

Team T-Force Delta RGB 16GB (2x8GB) 3200MHz CL16 DDR4

2 x Crucial P2 M.2 NVMe

ASUS ROG Strix Gold 750W

ASUS ROG Strix LC II 360 ARGB AIO Cooler

[ChrisLoudon]

25 minutes ago, Cal383 said:

Try another PSU - My PC does have the same PSU, which I can try if suggested, but I am reasonably confident that it is not the PSU.

Since you've tried pretty much everything else, the PSU is one of your last ports of call.

 

I've been building PCs for almost 30 years and can't stress enough how not to overlook the PSU or PSU power cables as a possible source of issues.

 

One of my most recent PC related headaches boiled down to the PSU. It was only when I removed the PSU and tried to unplug the PCIe power cable where I discovered the cable was melted to the PSU and wouldn't budge.

 

In my case, the PC would bot but as soon as any load hit the GPU and it wanted to draw any additional power over and above what the PCIe slot was providing, it was instant death!

 

 

[Cal383]

On 12/17/2024 at 10:54 PM, ChrisLoudon said:

Since you've tried pretty much everything else, the PSU is one of your last ports of call.

 

I've been building PCs for almost 30 years and can't stress enough how not to overlook the PSU or PSU power cables as a possible source of issues.

 

One of my most recent PC related headaches boiled down to the PSU. It was only when I removed the PSU and tried to unplug the PCIe power cable where I discovered the cable was melted to the PSU and wouldn't budge.

 

In my case, the PC would bot but as soon as any load hit the GPU and it wanted to draw any additional power over and above what the PCIe slot was providing, it was instant death!

 

 

Thanks for your response Chris, I appreciate the input and I did end up swapping the PSU just to be sure on your advice.

 

It ended up that the motherboard was shorting to the case - everything works with all the original components when I isolate the motherboard from the case.

 

Super weird.