Question PC won't boot even after changing most hardware

[boomy123]

I have a pretty old prebuilt computer (IBP from ~2013) that was running until recently. I updated the PSU and GPU, before leaving it for a while after building a new system. I recently started to let my son use it, but it just died out of the blue one day. I could turn on the system, but just the fans run and LEDs light up without booting to BIOS or displaying anything. I figured that something in the system probably went bad. I bought some new hardware to put in it (new MOBO, CPU, RAM, and storage), and when I try to run it on the new hardware, it has the same issue. The PSU, GPU, and hard drive remain unchanged.
The new hardware is this:

Motherboard: MSI B450M PRO-VDH MAX Micro ATX AM4
RAM: Corsair Vengeance LPX 16 GB (2x8GB) DDR4 3200 CL16
CPU: AMD Ryzen 5 3600 3.6 GHz 6-Core
PSU: CX600M (purchased around 2016)
Storage: Samsung 980 Pro 1 TB M.2 and a super old 1TB HDD WD Blue
GPU: Gigabyte GTX 1080 Turbo OC 8GB

I have tried everything on the sticky'd post about diagnosing not booting systems (reseated everything, checking for broken or bent pins, stripping down to just the cpu and one stick of RAM), but the issue persists. However, since we have a new motherboard, I can now see a new piece of information! Now, when I boot the system, I get a solid white light in the EZ Debug CPU LED area of the MOBO.

I am speculating that the PSU may have given out, but I am confused how the motherboard and case would still have power. Is it possible for the CPU power wire to give out, but not the other wires? Should I just bite the bullet and buy a new PSU and test it out? I think the BIOS supports the new CPU, but I am not 100% sure. I would appreciate any advice or insight on how to proceed on this, thank you!

 

[CountMike]

I have a pretty old prebuilt computer (IBP from ~2013) that was running until recently. I updated the PSU and GPU, before leaving it for a while after building a new system. I recently started to let my son use it, but it just died out of the blue one day. I could turn on the system, but just the fans run and LEDs light up without booting to BIOS or displaying anything. I figured that something in the system probably went bad. I bought some new hardware to put in it (new MOBO, CPU, RAM, and storage), and when I try to run it on the new hardware, it has the same issue. The PSU, GPU, and hard drive remain unchanged.
The new hardware is this:

Motherboard: MSI B450M PRO-VDH MAX Micro ATX AM4
RAM: Corsair Vengeance LPX 16 GB (2x8GB) DDR4 3200 CL16
CPU: AMD Ryzen 5 3600 3.6 GHz 6-Core
PSU: CX600M (purchased around 2016)
Storage: Samsung 980 Pro 1 TB M.2 and a super old 1TB HDD WD Blue
GPU: Gigabyte GTX 1080 Turbo OC 8GB

I have tried everything on the sticky'd post about diagnosing not booting systems (reseated everything, checking for broken or bent pins, stripping down to just the cpu and one stick of RAM), but the issue persists. However, since we have a new motherboard, I can now see a new piece of information! Now, when I boot the system, I get a solid white light in the EZ Debug CPU LED area of the MOBO.

I am speculating that the PSU may have given out, but I am confused how the motherboard and case would still have power. Is it possible for the CPU power wire to give out, but not the other wires? Should I just bite the bullet and buy a new PSU and test it out? I think the BIOS supports the new CPU, but I am not 100% sure. I would appreciate any advice or insight on how to proceed on this, thank you!

By changing all those parts it's same as building new system and should be approached and executed same way.
Any PSU can go partially bad, there are dozen or more different voltages and connections, if any of them is bad system as a whole will not. In your place I would try with known good and compatible PSU while doing "Breadboard" test, assembling part by part outside of the case.

 

[Reality_checker]

It sounds like the PSU is bad (or at least the cable that supplies power to the CPU).

If there is a spare CPU power cable that came with the PSU, try replacing the current one with that one.

Verify that you are using all the correct PSU cables. You should use only the cables that came with your PSU, not 3rd party ones.

Verify that the CPU cooler is plugged into the CPU Fan port. Most motherboards will refuse to boot if there is nothing plugged in there.

 

[boomy123]

Thanks for the replies! The CPU fan is spinning and the motherboard LED is on, so I assume power is going fine to all that stuff. Even though it is a modular PSU, I can't find the spare CPU cable I bought a new one today and will test it tomorrow. Thanks for your help!