[SOLVED] PC won't boot to BIOS, no signal, out of ideas ?

[Insomnis]

CPU: Ryzen 3300X
Mobo: MSI X570-A Pro
GPU: GTX 1660 SUPER / NEW: GT1030
RAM: Corsair 2x8GB 3200Mhz Vengeance
PSU: Corsair 750W / NEW PSU: Gigabyte 850W
Storage: 1TB Samsung Evo m.2 nvme, 1TB Western Digital m.2 nvme
Age: Almost 2 years

The problem begun slowly, the PC would randomly just go into this idle state and the monitor would go black (no signal). Then it became permanent before I could diagnose much. Temps were fine, nothing OC, everything looked fine before I was no longer able to boot into the OS.

Cut to now, the PC turns on and the ram RGB lights up but the screen on the NZXT Kraken AIO cooler doesn't. The motherboard cycles the error LED lights in about 3 seconds and they all stay off. However the monitor stays black (no signal). All the fans turn on, case, chipset, radiator. However it seems like the AIO pump isn't coming on, more on that. It will stay in this idled state until I hold the power button to turn off the PC. I also noticed there's no power going to the USB ports on the motherboard, which could mean the internal USB the CPU cooler uses is also not working.

Monitors - Working
I tested both my monitors with HDMI on my laptop and they work fine as well as the cable I have been using on the PC.

Peripherals - Working
I have removed every peripheral, wifi card, secondary m.2 drive. I will try no drives at all.
I tried booting while the mobo was bread boarded with no fans except the CPU cooler connected. The mouse, keyboard, external soundcard all work fine with my laptop.

Power Supply - Working
I replaced the PSU, my initial thought was the PSU was failing. The new PSU (850W) made no difference. I tried all brand new cables, even spares on the old PSU before it was replaced.
I've tried different power cables to both PSU and wall outlets.

Graphics Card - Working
My very first diagnosis was the GPU had failed, so I bought a cheap replacement and had no luck. I tried both DP and HDMI, multiple cables and both monitors. I tried both GPUs in both PCIE slots on the motherboard. I tried booting without a GPU to see if it possibly booted a little further.

RAM - 80% Working
I'm unable to test the RAM on another PC however I have tried each stick in all 4 slots and they always light up. The PC hadn't been moved or opened when the problems began. I've reseated the RAM numerous times.

CPU - 50% Working
I took the cooler off of the CPU and cleaned the old thermal paste which was fine, not to much or little and it wasn't dried up. The CPU pins were all there and straight, nothing visually wrong with it at all, it looks brand new.
However I can't rule it out as I'm unable to test it on another PC or mobo. Before the permanent black screen I was watching temps and the CPU temps were fine, the same with performance, it matched what I had been seeing since I bought it about 1.5-2 years ago. I don't overclock my gear.

Motherboard - 40% Working
I bread boarded the mobo, hooked up PSU, CPU, GPU, RAM and M.2 boot drive. I tried with both RAM, and 1 slot at a time each. I checked over the entire board about half a dozen times now and there's zero signs of malfunction, everything is straight and intact.
All standoffs are there for the board as well.
I powered on using a paperclip on the PWR+/- to rule out a faulty power switch on the case.
I tried powering up with the CPU cooler 3-pin connection in both CPU_fan and PUMP_fan which the manual says either can be used. I tried the cooler internal USB connection on both internal USB 2.0 sockets.

Case - Working
I ruled out the power switch for the case when I bread boarded the mobo.

AIO Cooler - Unknown
Im unsure whether or not the cooler is faulty and if it's able to stop the PC from reaching BIOS and leaving it stuck idling. The screen doesn't light up, and while bread boarded I put my ear very close to it and the radiator and couldn't hear anything at all. I'm not sure if this is due to the PC not booting properly, I would have thought the AIO would come on as soon as there was power to begin cooling the CPU right away.

I really need some help, I've got in contact about warranty on the CPU and motherboard.
Do I try a cheap CPU cooler while I wait?

Is there anything more I can try without spare CPU or mobo?

Thanks

 

[popatim]

If you have a Voltmeter then check your voltages at the big 24 pin connector. Black lead of the meter on the case and use the red lead to prob with.
Voltages should be within 5%

If the wires are colored then they should conform tot he ATX Specs. Yellow is 12v, Red is 5v, Orange is 3.3v, Black is ground/0v, & Blue -12v Otherwise google for the pinout and their voltages.
The Grey Wire and Green wire have special functions. Green wire turns the PSU on ( Remember the power switch connects to the motherbd) and the Grey wire is the Power OK signal from the PSU once the voltages stabilizes and tells the motherbd its Ok to boot up.