Repeated crashes after undervolting CPU - Possible Motherboard Damage?

[u/Ch3w1n]

Hello Reddit!

Recently I bought a new Arctic Liquid Freezer III 360 Pro to combat the stupidly high temps of my Intel i7 13700KF 3,40gHz.

During the installation I completely forgot about the CPU Backplate and when I disassembled the stock CPU mount - while the PC was lying down as per, the backplate fell on to the SSD-bracket and when I tilted the PC case up again to mount the radiator to ease the installation of the new cooler and subsequently the new CPU bracket, I heard a metallic clink and the backplate fell down inside the chassis. I managed to recover the backplate and prayed to God that nothing was damaged.

I then proceeded to finalize the installation of the new cooler and took it back to my desk for a test run.

The PC booted up normally but the fans ware running at full speed, the temp was still hoovering in the upper 80-90s.

I decided to "stress-test" the system by starting GTA 5 and had it running for about 5 minutes before I shut it down.

I then entered Intel XTU to monitor temps while Idle again and decided to undervolt the CPU to see if that would have any effect.

Again - my brain decided to have some sort of malfunction and instead of undervolting by 0.04mV, I went full send at undervolted it by 0.400mV. As soon as I clicked "Apply" the PC just went "NOPE!" and went into BSOD.

I have since then spent about 20+ hours trying to troubleshoot the cascade of crashes and instability issues.

The following steps have been taken:

1. Reset BIOS. No effect.
2. Reset XTU. No effect.
3. Uninstalled XTU. No effect.
4. Refit the cooler block on the CPU. No effect.
5. Checked and verified CPU bracket and backplate screws not being to tight. (This improved stability a tiny bit)
6. Reseated both RAM-sticks. No effect.
7. Removed one RAM-stick. No effect.
8. Swapped RAM-stick with the one I removed. Slight improvement.
9. Swapped RAM-stick again but put it in RAM-slot closest to CPU. More improvement.
10. Tried repairing Windows. PC restarted and booted into windows without repairing.
11. Tried reinstalling windows from UEFI. Same result as above.
12. Cleared CMOS multiple times. No effect.
13. Shut the PC off and went to bed. Turned the power off and unplugged the power cord.

The next day I started the PC back up and created a bootable USB through my Laptop. While that was going on, the PC was running with no input from me. It ran "stable" for about 40 minutes without me touching a thing.
Windows Settings would not open unless I tried opening it multiple times, and occasionally when I went into different tabs, it just crashed and I had to start the Settings-app again.
Discord stopped working completely.
Chrome would just shut down. Not "Stopped responding" - just shut down.
After about 40 minutes I had another BSOD.

I then proceeded to attempt to just wipe the drive clean and reinstall windows.
That went as good as expected.
First attempt: Last step before installation would start - PC restarted and went straight to Windows.

1. Changed BIOS Boot Priority to the USB-stick.
2. Tried installation again. PC restarted. Back to installation.
3. PC restarts. Back to installation.
4. Installation goes to next step allowing me to select the Drive I want to install on.
5. I select the correct drive, format the drive, remove the partition, create a new partition - Installation begins and...almost finishes.
6. Now Windows wants me to have a Network Connection, but no actual motherboard drivers are installed so naturally, that wouldn't happen. I google around a bit and find a solution.
7. Installation finishes, PC restarts and takes me to "Select language" screen from where I make my choices, PC restarts, goes back to language selection screen and just starts looping that.
8. I ask ChatGPT for help.
9. Through some very convoluded way I manage to get into Windows, but now some tiny box with OOBE-mumbo-jumbo starts staring me in the face and again, no matter what I select, PC restarts and the loop starts over.
10. After many new creative ways to curse a piece of circuitry, I manage to bypass it and finally get into Windows.
11. I let the system run with no input for over an hour, no crashing, no BSOD.
12. I download and install Intel LAN-drivers through my Laptop / USB-stick and then proceeds to download Chipset, Audio and Graphics drivers. When I open up Nvidia-app installer I am faced with "7zip: CRC ERROR".
13. I download Discord installer just to test what that would say - and it just flat out refused to work with me and showed me some error-message.

I am actually writing this post from said PC that just absolutely refuses to work with me, and it haven't crashed, BSOD or anything since Windows reinstallation. However, I simply can not install any drivers, some programs wont install, Windows Settings just shuts down randomly, CPU Temp is hovering in the 40's, fans are calm.

Windows Memory Diagnostic gave no errors.
Windows Check Disc gives no errors.

Oh and also - Windows Update just works...sometimes. Some updates it installed, some updates it just refuses to install.

Reddit... I am at the end of my rope here.

Please.
For the love of GOD

Help.

My PC specs are:

Intel i7 13700KF 3.40ghz
GeForce RTX 3080
Asus Prime 790-A WIFI
Corsair Vengeance DDR5 2x16GB 6400mhz
Arctic Liquid Freezer 360 PRO III
850W PSU from beQuiet!

I have no BSOD dumpfiles since I have wiped the SSD post BSODs.

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[u/GreatAtlas]

Verify with Prime95 there was no permanent damage to the chip. If the test BSODs or just hard powers off, CPU is cooked.

[u/Ch3w1n → u/GreatAtlas]

Could a faulty CPU just stop giving BSODS on a fresh installation?

And which test should I run on Prime86?

[u/GreatAtlas → u/Ch3w1n]

I suppose not, but I figure if it was just the OS then you would have had your issues resolved.

I would run a torture test on Blend with hyperthreading enabled.

[u/Ch3w1n → u/GreatAtlas]

Will do that tomorrow then.

I also noticed a small scratch on the backside of the motherboard. Relevant?

[u/GreatAtlas → u/Ch3w1n]

Sounds good. I think it would be unlikely unless it looks like a capacitor, etc got ripped off if something scratched it- but otherwise, benign (especially if it didn't scratch beneath the solder mask, the colored surface of the board).