[SOLVED] Computer fails to POST, VGA light on

Aug 28, 2022
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Hello everyone, my computer recently failed to boot, instead choosing to scroll text reading: "SetVariable██ : UnsupportedInitCbuiVariable : Unsupported". It scrolled and quickly filled the screen, with variations to the full blocks.
Image: https://cdn.discordapp.com/attachments/910007285319864380/1013579052470259782/IMG_0634.JPG

When this happened, I attempted to fix it and was able to restore it by flashing the BIOS. It then worked for 2 days before experiencing the same problem on the 19th of August.

Now, it is failing to POST, but is no longer giving any signal through the graphics card HDMI port. I have attempted to replace the parts implicated by the lit VGA light to no avail.

I keep a troubleshooting log and have posted the relevant part below.

Any help would be appreciated.

Log below:

[Specs when problem began]
  • AMD Ryzen 7 3700X (2 years old)
  • MSI X570 Gaming plus (2 years old)
  • 2060 Geforce RTX Ventus (2 years old)
  • G.skill 8GB ram (2 years old), Viper 8GB ’Steel’ (4-5 months old, replaced dead g.skill stick from 16 GB 2-stick package)
  • Rosewill Hive-550S (2 years old)
19 August 2022

Issue: White “unsupportedcbuinitvariable” text scrolling on boot without post

Attempted:

Reset motherboard memory by removing onboard battery and shorting metal bits
Remove, clean, put back [GPU, RAM, all power cables]
Flashing BIOS to 3 different versions (supporting windows 11)

Status after:
On attempted boot, lights turn on and fans spin. No power to USB ports. Lights on motherboard turn on in sequence: CPU, VGA+BOOT, none (normally would POST at this point), VGA. CPU fan increases speed, while motherboard integrated fan stops. No POST, visual or audio.

//

Flashing BIOS to version 7C37vAE (no windows 11 support)
No progress

//

28 Aug 2022

Replaced

  • Motherboard
  • Graphics card
[Specs after motherboard/graphics card changes]:
  • AMD Ryzen 7 3700X (2 years old)
  • MSI X570 Gaming plus (New)
  • 2060 Geforce RTX Ventus GP edition (New)
  • G.skill 8GB ram (2 years old), Viper 8GB ’Steel’ (4-5 months old, replaced dead g.skill stick from package)
  • Rosewill Hive-550S (2 years old)
Attempted: Reseating CPU, Clearing CMOS, Flashing BIOS, checking wires, shuffling RAM sticks, booting with SSD removed.

No progress towards POST, just gets stuck with the fans spinning and the VGA light on. No power to peripherals either.

Possible issues as of 28 Aug:
  • CPU has died?
  • 2 damaged PCIE ports (4 in total)?
  • Incompatibility issue somewhere?
  • Power supply insufficient to graphics card or CPU?
  • A cable is damaged?
  • Faulty (both new and old) graphics card?
 
Sep 25, 2022
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Yes, but you might not be happy about it. I had to replace both the CPU and motherboard, and then the problem was gone. I am not sure exactly what it was, my guess is a flaw with the cpu mount somewhere. I would recommend remounting the CPU and ensuring it sits there properly in its slot.
I replaced my CPU today (ryzen 3600-> 5600G).

BIOS came up right away and Windows booted on the first try. You were right, it was a CPU issue and looks like it is fixed now

Thank you for logging your troubleshooting process, it was really useful and saved me a lot of time!

Cheers!
 
Last edited:

helpstar

Polypheme
check all while no HDD/SSD is installed

try different cables/ports from your PSU
did you connect PWR1 and PWR2? (4pin and 8 pin)

8pin power connected to the GPU and not only 6pins?

did you run the GPU in the upper slot with the new board?
die you try 1 RAM installed in Dimm slot A2? (2nd slot from CPU)

breadboard (outside the case) your setup with minimum components

replacing the power supply would be the next thing
after that, the CPU
 
Aug 28, 2022
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What you have said here are mostly the same conclusions I came to.

Breadboarding attempts with each motherboard-graphics card combination always has the same error.
I am not sure what you mean by PW1 and PW2, there is only one point to connect the GPU cable to the power supply. The cable then splits into two ends, neither of which fix the problem.
Every boot attempt since the first few has been with one stick of ram, and changing which one has no effect.
The issue is the same if the graphics card is mounted in the first or second PCIE slot.
The gpu’s 8 pin connector is properly attached.

I will investigate the power supply and see if it’s working properly.
 
Sep 25, 2022
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Any update on this?
Was it the PSU?

I'm having the same issue with an MSI b450 board and Ryzen 5 3600
 
Last edited:
Aug 28, 2022
4
0
10
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Yes, but you might not be happy about it. I had to replace both the CPU and motherboard, and then the problem was gone. I am not sure exactly what it was, my guess is a flaw with the cpu mount somewhere. I would recommend remounting the CPU and ensuring it sits there properly in its slot.
 
Aug 28, 2022
4
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10
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I also have here a kind of test log that I kept. It might help you somewhat

————————————-—19 August 2022——————————————


Issue: White “unsupportedcbuinitvariable” text scrolling on boot without post

Attempted:

Reset motherboard memory by removing onboard battery and shorting metal bits
Remove, clean, put back [GPU, RAM, power cables to all but CPU]
Flashing BIOS to 3 different versions (supporting windows 11)


Status after:

On attempted boot, lights turn on and fans spin. No power to USB ports. Lights on motherboard turn on: CPU, VGA+BOOT, none, VGA. CPU fan increases speed, while motherboard integrated fan stops. No POST, visual or audio.

//

Flashing BIOS to version 7C37vAE (no windows 11 support)
No progress

//

28 Aug 2022 - New Mobo, Graphics card

Replaced
  • Motherboard
  • Graphics card
[Specs after motherboard/graphics card changes]:

  • AMD Ryzen 7 3700X (2 years old)
  • MSI X570 Gaming plus (New)
  • 2060 Geforce RTX Ventus GP edition (New)
  • G.skill 8GB ram (2 years old), Viper 8GB ’Steel’ (4-5 months old, replaced dead g.skill stick from package)
  • Rosewill Hive-550S (2 years old)
No progress towards post, just gets stuck with the fans spinning and the VGA light on. No power to peripherals either


Possible issues:
  • CPU has died
  • 4 damaged PCIE ports?
  • Incompatibility issue somewhere
  • Power supply insufficient to graphics card or cpu
  • A cable is damaged?
  • Faulty graphics card?


Computer diagnosed to have 2 faulty motherboards by evergreen computers

Their notes:

Used known good RAM, GPU, PSU
Used provided CPU and motherboards
1,2 beep code with both motherboards
Stalls on VGA light
Known good CPU was used, same VGA light but no beep codes
Could not diagnose further bc no AM4 motherboard

“Conclusion is both motherboards are faulty. Possibility of provided CPU being faulty.”

//

Motherboard #2 exchanged for new motherboard

Thu Sep 1

(Motherboard #3 arrives)


Removed all parts
Installed CPU + CPU fan to new motherboard
Installed RAM
Motherboard is mounted in case
Power attached: CPU, Motherboard
Graphics card (new) installed
SSD installed
Power connected to graphics card
Other minor cables connected (fans, front panel, audio)
Main power cable connected
HDMI connected
Activate power

Attempt boot
  • No POST
  • Cycles through debug LEDS twice, then all debug lights off
  • No power to peripherals
  • SSD warms to the touch
  • Fans spin
Reboot, attempt again
  • Same result
Graphics card replaced with old, attempt boot
  • Same result
CPU, CPU fan removed to check for pin damage

No visible damage

Both returned to motherboard, attempt boot
  • Original problem (VGA light)
Graphics card changed to new, attempt boot
  • Original problem (VGA light)
[Possible that damage was incurred mounting the CPU fan? It takes a bit of force to get it to snap in.]
[What was the problem that prevented POST the first time on Motherboard 3?]
[??? I am lost here]


Possible issues:
  • Faulty CPU has fried 3 motherboards
  • Faulty (my) PSU has damaged motherboards such that they will not work even with a good PSU
  • Unrelated problem prevented POST once on newest motherboard, and I damaged all motherboards the same way during CPU fan installation
  • Something else
Got mad, hit computer :/

Attempt boot

  • Cycles boot lights twice, problem with no LEDs is back
[???]

Attempt boot, same problem x2

Attempt boot

  • VGA light is on again???
Cleared CMOS by shorting pins

Attempt boot, same problem x2

Cleared CMOS by shorting pins

Attempted boot
  • Cycled LEDs on motherboard twice
  • All LEDs off
  • No POST
No change on next 3 boots

Graphics card changed to old

Same on boot x3

Both graphics cards installed

On boot
  • Fans for both cards run [PSU is ok?]
  • No signal from either
  • No post
  • No LEDs
Fri Sep 2 - New PSU

Misc testing, no progress

PSU testing log

Shorted pins to cause it to turn on

  • Note: This was done incorrectly, the PSU was fine
3.3V plug had voltage 2.2V

12V plug had voltage 5V

Replaced PSU

New PSU installed, still no boot

Problem is the same, no VGA light

Next to replace is CPU

Sun Sep 4 - CPU arrives

Removed

  • CPU fan
  • GPU
  • CPU (old)
Installed new CPU, breadboarded with old PSU, new GPU, old RAM, old SSD

Boots normally to windows :)


Summary

Replaced
  • Motherboard (got one DOA, so did this twice)
  • GPU
  • PSU
  • CPU (fixed)
Time spent: ~15 hours over ~2 weeks

Lesson: Be careful when mounting the CPU fan (do it before putting the motherboard into the case if possible) or else

Still Pending
  • Replace thermal paste
 
Sep 25, 2022
2
0
20
1
Yes, but you might not be happy about it. I had to replace both the CPU and motherboard, and then the problem was gone. I am not sure exactly what it was, my guess is a flaw with the cpu mount somewhere. I would recommend remounting the CPU and ensuring it sits there properly in its slot.
I replaced my CPU today (ryzen 3600-> 5600G).

BIOS came up right away and Windows booted on the first try. You were right, it was a CPU issue and looks like it is fixed now

Thank you for logging your troubleshooting process, it was really useful and saved me a lot of time!

Cheers!
 
Last edited:

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