[SOLVED] System failed to boot with "VGA" motherboard lights on, but with a twist

Exploding PSU

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Hello everyone. This thread was somewhat of a "sequel" to the post here, just with a different issue.

TLDR : PC fails to boot with the VGA LED on the motherboard lighting up, but no GPU-related fixes seems to fix the problem.

To recap, I cleaned my PC by disassembling it completely, removing every parts, then put them back together. It worked fine after that, only the CPU was a bit on the hot side. Turned out, I forgot to apply thermal paste to the CPU (my bad), so I removed the cooler, applied some thermal paste, and the PC worked flawlessly since then... Until these last few days, when the PC refused to boot EXCEPT if I reset the BIOS (the jumper thingies). Here are the symptoms :
  • After the power button is pressed, the PC turns on. All 3 of the GPU fans spin. The RAM's RGB lights up in rainbow mode. The motherboard's "CPU, DRAM, and BOOT" lights up, in that order one after another. The monitor then lights up, then something which I can only describe as "blinking underscore" appears in the top left of the screen. Nothing else appears on the screen. After about 3-5 seconds, the "underscore" would stop blinking.
  • Right after the underscore stops blinking, 1 of the GPU fans (the leftmost one, the one closest to the back of the PC) would stop spinning. The other remaining fans would continue to spin.. At the same time, the "VGA" light on the motherboard would light up indefinitely.
  • At this point, the PC is frozen completely. The keyboard is unresponsive (can't even enter BIOS). Restarting the PC will simply lock it up again.
Some things to note :
  • The PC can be booted ONLY after a BIOS reset. After the BIOS is reset (by shorting the jumper behind the GPU), the message (paraphrasing here) "Press F1 to enter setup, F2 to load default values to continue" would appear right after turning on the PC. Pressing the F2 button will restart the system and the PC would boot into Windows just fine. Shutting down the PC / entering Hibernate mode / power cycling the PC would cause the PC to lock up again with the same symptoms as above. Sleep mode is unaffected.
  • When the PC locks up, the "BIOS splash screen" (MSI logo that appears before Windows logo) wouldn't appear at all, it would jump straight to the "blinking underscore".
  • The keyboard's RGB lights sometimes lights up and sometimes don't when the PC gets stuck in the "blinking underscore" screen.
  • If I manage to boot into Windows, the PC works flawlessly. The GPU doesn't seem to have any problem (all benchmarks turns out fine) no BSOD or anything. Temperatures are normal. It's rock-solid, stable, and would run for days no problem. As long as I don't shutdown the PC, in which I would need to do the "reset jumper" ritual to get it running again.
Some things I've tried to correct the problem :
  • VGA LED lights up when the PC fails to boot, so it must be the GPU right? I've tried 3 different GPUs that I have on hand (a Vega 56, a GTX 970, and a GTX 1060 3GB, those were old working GPUs that I couldn't get myself to sell due to sentimental values). And what do I know, the PC still refuses to boot. Same symptoms. There's no way all 3 of my GPUs are damaged, right? Please note that by resetting the BIOS, the PC is able to boot normally with any GPU inside.
  • I use a "vertical GPU kit" with riser cables and stuff. I tried installing the GPU directly into the PCIe slot. Seems to have no effect.
  • Different GPUs react differently when the PC gets stuck on the "underscore" screen. The RX6800 XT has the leftmost fan stop spinning. The Vega 56 has both fans stop spinning. The GTX 970 and 1060's fans kept spinning.
  • Tried installing the GPUs without power cables connected, VGA LED still lights up. Also tried connecting the GPU's power cables but not actually installing the GPU, the GPUs fans run at full speed. All GPUs exhibit the same behavior. Still stuck with the same symptoms.
  • Cleaned the PCIe slot using some brushes.
  • Tried installing the GPUs into different PCIe slots, same thing.
  • Tried to boot the PC without any GPU. The VGA LED finally doesn't light up, but obviously nothing appears on the monitor. However, I guessed the PC still fails to boot, as I don't hear the "Windows logon sound" even after waiting for a long time (or after I blindly pressed F2 in case the "Press F2 to load default values" actually appear and the monitor simply doesn't show it). Not only that, the keyboard's RGB still randomly lights up / turns off, which is the exact same symptom as when the PC locks up. The "blinking underscore" is probably still there only I can't see it.
  • Reinstalled drivers when the PC successfully boots (after I reset the BIOS). Locks up after restarting the PC.
BUT WAIT, the PSU! I know I'm going to be asked about the PSU, so to rule out this being a PSU problem, I borrowed one of my mate's PSU he had lying around. It's a Gigabyte P750 PSU, and it's still brand new in box (he hasn't opened it yet). I replaced the PSU in my PC with that new PSU and.... same problem. Same behaviour actually, I could boot the PC only after I reset the BIOS.

So I'm basically at wits end. The VGA LED lighting up suggests that it's a GPU problem, but nothing GPU-related fixes I tried seems to solve the problem. Either I'm currently in a string of bad luck where all 4 GPUs I have are problematic and 2 PSUs I tried happens to be broken or something is wrong with my PC's setting. I have this fleeting feeling that it might be my classic mistake of missing a simple thing somewhere (like that thermal paste shenanigans I had before this one, my mind went all over the place thinking maybe my CPU or motherboard was dying and it turned out it was simply me forgetting to apply thermal paste). Currently the PC is running correctly, but I've left it on for days as I know if it were to shut down it would refuse to boot afterwards. Please note that before this problem appeared, the PC works completely fine.

Specs :

CPU : Ryzen 5 2600
MB : MSI X370 SLI Plus
RAM : T-Force Delta R DDR4 3000 32 GB(16x2)
GPU : Yeston RX 6800 XT
SSD : Samsung PM1725a 1.5 TB
HDD : An old 500 GB Seagate Momentus Thin
PSU : Seasonic S12G Gold
Cooler : Cryorig H7 QL

Any input is appreciated, thank you.
 

scout_03

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i would try to have this motherboard check since on first post cpu run without paste socket on motherboard could have suffer from high temp you may be on a way for a new board and let see if someone else any clue .
 

Exploding PSU

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the middle one also made sure you test with minimal parts like ram and check if cpu did not have bent pins at last this might lead to board issue .
Sorry. when I said "bottom one" I meant the middle one, the one directly below the "main" PCIe slot. The bottom-most one is just too close to the case floor to fit any GPU in it.

Alright, I'll give it a check. I'm sure there's nothing wrong with the CPU pins or something of that sort, but I'll check it. Will report back later.....
 

Exploding PSU

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the middle one also made sure you test with minimal parts like ram and check if cpu did not have bent pins at last this might lead to board issue .
Sorry for double posting, but I've checked the CPU and the socket and I see no damage (as much as I'm aware of). No bent pins or anything. I've also checked the RAM and every slot on the motherboard while I'm at it, and again couldn't see anything wrong. I don't see any blown capacitors or weird smell either (I've experienced blown PSUs so I knew how burnt electronics smell like).

After I put the PC back together it's still stuck on the "blinking underscore" screen, unfortunately.

So, maybe there's anything else I could check?
 

scout_03

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i would try to have this motherboard check since on first post cpu run without paste socket on motherboard could have suffer from high temp you may be on a way for a new board and let see if someone else any clue .
 

Exploding PSU

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i would try to have this motherboard check since on first post cpu run without paste socket on motherboard could have suffer from high temp you may be on a way for a new board and let see if someone else any clue .
Sorry for the late reply, but I maanged to find the root cause of the problem. And it's NOT even GPU-related.

TLDR : stray USB thumb stick caused the PC to lock--up during boot process. It's not even the GPU.

I was ready to send the motherboard back for repairs, I already called MSI and talked about their RMA program (which they denied, long story, classic), so I thought I was going to ask the local PC store if they could do something about it. I was unplugging all the USB cables that was connected to the motherboard in preparation of removing the motherboard from the case.

Then, it dawned on me : what if one of the peripherals caused the problem? Maybe something went so badly wrong the motherboard didn't know what actually happened so it simply light up the VGA LED light or something.
And the fact that the keyboard's RGB sometimes light up, other times it doesn't, this theory MIGHT have some merit (at least on my mind, I don't know how PC works exactly so I'm sorry if my thinking sounds ridiculous).

So I unplugged everything (the keyboard, mouse, a USB wifi adapter, the speaker, and a random 16GB USB thumb drive) and what do you know :

The PC booted up normally. The MSI logo returned, then the Windows logo, and straight to desktop. Not even the "Press F2 to load default values" prompt appeared. The blinking underscore thing did appear after the MSI logo then it disappeared after 3 or 4 blinks. I reconnected my mouse, shut down the computer, and tried turning on again. It turned on flawlessly on second try. So I reconnected my peripherals one by one, turning the PC on everytime I plugged them in, and turns out, the 16 GB USB thumb drive IS the culprit.

The moment I boot the PC with the thumb drive plugged in, the PC refuses to boot with the exact same symptoms (VGA LED on). Remove the thumb drive,and it's smooth sailing.

That thumb drive has been plugged in since... forever. But it was plugged in the front panel USB port, not in the back. Windows Explorer can't recognize the USB thumb drive when I plugged it in, so I'm not sure what's inside that USB. But, it's solved, that USB somehow prevents the PC from booting normally while making the UTTERLY MISLEADING VGA LED light up.

Here's my theory on what happened :

  1. The USB thumb drive is broken. Not sure what or how, but it's simply a piece of error device.
  2. I randomly plugged in the USB to the front panel USB port some time ago, which happens to be not functioning. Windows doesn't recognize anything plugged into that particular port, it's simply doesn't exist.
  3. The problematic thumb drive had been plugged into that non-functioning port, so Windows didn't know it's there and thus chugs along normally
  4. When I cleaned the PC some time ago, I randomly moved that USB thumb drive to the back port (the motherboard port), which is NOT broken. The PC can now read the thumb drive
  5. Whatever is in that drive caused the PC to lock up when it read / accessed it which made it refuse to boot somehow.
That's how I think it happened. I've been power-cycling the PC for millions of times since then and it turns on with no problem whatsoever. That USB thumb drive is the sole culprit. This problem is solved, unceremoniously.

Unfortunately, this is the second time I posted a thread in which the problem stems from my carelessness, after that thermal paste saga (I forgot to apply thermal paste and asked the forum if my CPU is broken). This time, a stray USB drive caused my PC to lock up.

As an extra, I tried to connect the USB thumb drive into my Lenovo laptop, and what do you know, it ALSO refused to boot (the Lenovo logo didn't appear at all, was just blank screen). Seems like the USB drive is a universal killer...
 

Exploding PSU

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check the name of this thumb drive if could have a lock option on it like these they need a password to unolck https://www.amazon.ca/encrypted-usb/s?k=encrypted+usb there call e3 thumb drive, good to know system work .
It's a standard garden-variety SanDisk 16 GB thumb drive. I'm not sure which model it is. I've used it before to transfer few PDF files, it worked just fine. I think it's somehow broken, maybe the connector or something inside it came loose. I simply threw away the thumb drive for giving me such a headache. This problem has been solved though, it's behind us now. System is rock solid, nothing to complain about.
 

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