If mods think this should be posted to a different reddit, just let me know
This is going to be a long one, but I am giving as much detail as possible.
To preface, I have been building PCs for fun since ~2015, so I know my way around troubleshooting to some extent, but this one has me stumped.
I custom built my newest PC around September/August of 2023 and it has been working amazingly and I think I have gotten a BSOD maybe three times since I built it, until Sunday (April 26th, 2026) when I was about to play some video games with a friend. He said I was having static in my mic, this is not uncommon for my Focusrite Scarlett Solo 3rd Gen (purchased June 2020), as audio issues are the bane of my existence.
The static affects both my microphone and headphones. Normally a restart will suffice, and usually the static occurs mostly while I watch YouTube (strangely has never happened during games). On rare occasions it still happens after a restart and completely unplugging my pc will fix it. It was on a good streak until the latest NVidia drivers (596.21 April 16th, 2026) and the static started happening about every day.
So I reinstalled the latest Focusrite drivers v3.27, and just in case checked Windows for any updates before restarting. There was only a defender update and then I restarted my PC. Went to the bathroom and came back to the lock screen, displaying the time and a black background. PC and KBM lights and fans on, but the keyboard and mouse inputs not doing anything.
Best idea I had was to hold the power button to turn it off, flip the PSU switch, wait for the mobo light to turn off, pull the pc two inches away from the wall, unplug the PSU, wait ten seconds, then replug, flip switch, and turn back on.
This is when it no longer made it to Windows or even the BIOS. Fans and lights turn on, instant yellow DRAM light on, no other post lights in any order. The fans were speeding up and slowing down constantly, so I spent quite a lot of time seeing if it was memory training for some reason. Then I tried the single stick of RAM method, I tried one of my two sticks at a time, in every single slot. I tried no RAM, same thing. I cleaned the slots as well. Then I removed the CMOS battery and waited ten minutes and put it back in. Strangely, this made the fans stay at a constant speed instead of fluctuating.
I tried updating the BIOS with the flashback feature. In the past I updated the BIOS one time in late 2025, before that it had the stock BIOS when I got it (which I just recently saw that some ASUS motherboards had a burning CPU issues). The BIOS update seemed to work as it stopped flashing after a few minutes. No change in the issue.
I went to a friend's to swap RAM as the biggest problem would be buying new RAM. None of his sticks of RAM worked in my pc, but both of mine worked in his, they showed up in task manager as 32GB at 6000 MT/s. His pc didn't even memory train (I wonder if it is because we have the exact same CPU and RAM as we upgraded at the same time) I didn't do a CPU swap as it was ~9PM on a Sunday and he wanted to work at midnight.
Fast forward to the next day (Monday April 27th, 2026), I checked the CPU/Motherboard pins and reseated the CPU, pins looked fine and can confirm the CPU gets hot if I turn on the system. The top of the motherboard has a dark spot, but I am unsure if it is a burn or some oil, see the pictures. This problem is the first time that I have opened the side panel since I built it, so I haven't fiddled with anything inside for two and a half years.
Other than that, I am stumped and this post is really to see if I can fix it before ordering a replacement motherboard, as I am leaning towards the motherboard being the issue and not the CPU or RAM. My question is, why now? I even ordered one of those post code speakers and it doesn't even beep a code. I got a pack of five, so either none of them work, or the motherboard isn't even sending a post code error for me to hear.
Any suggestions are appreciated. I am stuck using a low end laptop for work and a Steam Deck for gaming, so I have some patience before I start buying replacement parts.
Pictures and proof of purchase: imgur.com/a/kMTGV0E
PC Build:
Windows 11
CPU: Ryzen 9 7900x
Motherboard: Asus Prime X670E-Pro WIFI
GPU: Gigabyte Eagle OC RTX 4080
PSU: Corsair RM1000e (2023)
RAM: G.Skill Flare X5 32GB 6000 MT/s