Question I'm building a new PC, and now I've found myself with 2 CPUs, 2 mobos, 2 of almost everything but 0 POSTing configs. I'm experienced but at a loss.

Apr 13, 2022
Hello everyone, glad you're here, I'm really, really confused right now. I bought a new system for gaming and light 3D rendering online, and upon assembly it just lit up the CPU EasyDebug light red on the motherboard and rebooted in a cycle, without any kind of video output. Specs below:

i5-12600K CPU
MSI PRO Z690-A DDR5 Motherboard
GIGABYTE Gaming OC GeForce RTX 3060 12GB GPU
1x Crucial 16GB DDR5 4800 - Model CT16G48C40U5 SDRAM
SAMSUNG 980 M.2 2280 1TB PCI-Express 3.0 x4 M.2 SSD
EVGA 600 GD 100-GD-0600-V1 600 W ATX12V / EPS12V 80 PLUS GOLD PSU
Noctua NH-U12S Redux High Performance CPU Cooler
Metallic Gear Neo Silent Mid Tower ATX Chassis Case

Well, the CPU light was on, and this motherboard had 2 CPU power connectors, something I haven't seen before as I built the rig I'm writing this a few years ago, and this new one is my most expensive build by far. So I went to the local computer store and picked up a:

EVGA 220-P5-0750-X1 SuperNOVA 750 P5 750W PSU

that has two CPU connectors and is more appropriate to the build anyway. I'll just return the 600W PSU. But... still no boot. So I breadboard the system, strip it down to minimum configuration, even remove the GPU and replace it with my old 1660 super, still boot looping. 3060 works fine in my current system.

Great, the LED is correct, the CPU is bad, so I go down to the local store and buy:

i3-12100F CPU
WD WDS100T3X0E Black SN770 1TB NVMe Solid State Drive M.2 2280 PCIe Gen4 x4 SSD
ASUS PRIME B660M-A D4 Motherboard
a second Crucial 16GB DDR5 4800

Thinking I'll upgrade the system I'm using (passing it on to my wife) with these new parts once the RMAC process is over, and I can use the i3 in the new one in the meanwhile. Might as well swap the m2 and RAM as well just in case, local store has a permissive 14 day return policy. Only... THE CPU LED IS STILL ON! The system behaves exactly the same with the i3 installed as it did with the i5, and I did clean with isopropyl and reapply from a brand new arctic silver it each time I reinstalled the CPU. Well, at least I have another motherboard, so I install that with the i5 and a DDR4 stick I know works because I'm using it now... and it stays on, fans spin, but there's no video output. Same with the i3.

Since then I've tried every possible combination. I've tried both CPUs on both motherboards, I've tried both GPUs in different configurations (fans spin on both GPUs in both mobos), I've tried both PSUs, I've tried just one of each of the DDR5 sticks, I've tried one each of the working RAM sticks from this system in the DDR4 mobo, I've tried both M2 drives, either, or just a old 500GB HDD, or no drive on both boards. I've gone over this checklist.

I'm pulling my hair out and I feel like I'm losing my mind. Do you all have any ideas? Because I'm fresh out and the window to return and exchange parts is closing around me quickly.