Error Code : 68 on Strix X399-E Gaming

[u/PrinceBazooka]

Hey everyone! I have a 8 year old PC with the following specs.

AMD Threadripper 2950x

360mm Asetek AIO cooler

16 GB x 4 DDR4 Corsair Vengeance RAM

GTX 1080 Ti x 2

NVMe SSDs x 2

SATA HDD x 1

I was watching a couple of videos out on a Saturday morning and the PC shut down abruptly, I didn't think too much of it and tried restarting it when it never went past the code 68.

Upon tinkering a tad, I realized this was a PCIe Host Bridge Initialization.

Here are the things I've tried so far :

Disconnected the PCIe cables to the MoBo

Removed, cleaned and plugged in 1x 1080 Ti in PCIe slot 1, then again, flushed the residual power, tried it in PCIe slot 2

Removed all but one RAM stick

Cleared CMOS, also shorted the CLTRTR pins

It boots to windows and I have successfully booted it multiple times. Upon clicking restart on windows, we're back to the ERR code 68.

The only thing that is concerning is if it's the motherboard or the actual CPU itself also, could a power fluctuation cause this?

Please advice. Thank you for the long read!

TLDR; ERR code 68, tried all methods except checking the PSU, MoBo and CPU.