[SOLVED] PC froze multiple times, now won't POST, no beeps but fans on and lights up

[Sealion987]

So I changed a lot of my pc about 6 months ago now, and it's been a dream since then, up until now.
It froze randomly and would only power off by switching off the psu. I rebooted, updated the BIOS as a fix and it seemed fine.
The following day the same happened, yet when I attempted to start it back up the RGB lights (mobo, RAM, cooler and fans) came on and the fans spun up, but nothing else. No display output on either monitor from any source, gpu or mobo, no beeps from the little speaker in the case, and none of the warning LEDs on my mobo. The keyboard and mouse also no longer light up. All the threads I've read so far about this are about new builds, where as mine is half a year old.
Specs:
CPU : Ryzen 7 3700x
Mobo : ASUS B450f Gaming
RAM : Corsair Vengance 2x8GB
PSU : Corsair TX750M
GPU : Gigabyte GTX 1080
Booting off a Sabrent 1TB M.2 nvme drive

 

[T_T]

The first step in a POST/Boot problem is always to build your pc out of the case. This will rule out any electrical shorts being caused by the case. Strip down your PC, leaving installed your CPU and it's cooler/fan. Next, follow these steps:

1. Place motherboard on cardboard, wood, or any non-conductive surface.
2. Install only one DIMM, into the slot closest to the CPU.
3. Install your PSU (don't forget about the 8-pin CPU connector).
4. Install your GPU and plug in the connector(s).
5. Jump the Power Switch pins.
6. Connect your monitor.

If the build successfully reaches POST, wait for the POST to finish, then shut down. Swap your DIMMs then test again.

 

[Sealion987]

The first step in a POST/Boot problem is always to build your pc out of the case. This will rule out any electrical shorts being caused by the case. Strip down your PC, leaving installed your CPU and it's cooler/fan. Next, follow these steps:

1. Place motherboard on cardboard, wood, or any non-conductive surface.
2. Install only one DIMM, into the slot closest to the CPU.
3. Install your PSU (don't forget about the 8-pin CPU connector).
4. Install your GPU and plug in the connector(s).
5. Jump the Power Switch pins.
6. Connect your monitor.

If the build successfully reaches POST, wait for the POST to finish, then shut down. Swap your DIMMs then test again.

OK firstly thanks for your help. I did as you said and both DIMMs were fine both in the first slot and when I returned them both to the recommended slots it was fine, booting through with no errors. I am currently reassembling it all in the case, hoping it will be OK. Any idea what might have caused it originally?

 

[T_T]

Gremlins... j/k. Hard to say, really. Sometimes if the computer is moved or bumped, it can cause a slight displacement. For example, a PC I built about a year ago was running just fine, then a few days ago the damn thing was freezing and rebooting. When i did my internal checks, i found a couple of loose motherboard screws. Did the external build and stress tested the system. Tests passed so I put everything back into the case and tested again. Sometimes this stuff happens is all I can say.