Question Power cycling, and a plethora of post codes

Jun 29, 2019
So this is a phantom problem that I had late 2017, that didn't get resolve duntil February 2018. For whatever reason, it's back.

For a back story: I built this PC in September of 2017, late October/early November I started it up, and it power cycled until I turned it off. Fans spin, RAM lights up, GPU lights up, motherboard sends some post codes (15, CO, 67, a bunch of different ones in rapid succession, ending with 90), rinse and repeat. I took it all apart a hundred times, inspected CPU pins, made sure everything was in correctly, and nothing. No results. So I RMA'd the CPU. It worked for 8 hours, I went to bed, got home from work the next day, and nothing. I RMA'd a 2nd CPU, DOA. RMA'd a new set of RAM, no results. I returned my motherboard and bought a better model that was on sale and cheaper at the time, but still no results. Months later I said screw it, and took it to a shop. They charged me $150 to tell me they didn't know what they did, only that it was working the next day. When I got there, they said they had reseated everything, cleared the CMOS, tried different RAM, and still got the same result, until it finally posted. It was fine from February 2018, until today (June, 2019).

Last night, I played Risk of Rain for a few hours and listened to Spotify. I didn't have 40 programs open, I wasn't mining for coins. This morning, I got up and tried turning it on, and the same thing happened. Lights, post codes, power cycle. No signal to my displays, no lights on my peripherals. Can't get into the BIOS to flash a new one, and I've tried clearing the CMOS as well as replacing the battery. I took everything out, preformed a much needed dusting, inspected for any damage, and nothing. All the parts are in tact, no CPU pins are bent. I've tried booting with each stick of RAM, and no sticks as well, but I'm still getting the same results. If I have to take it to a shop that'll charge me to say they don't know what they did but it works, I will. But I'd really rather not.