PC loses signal to monitor, crashes.

[Shirone]

So my computer has been losing signal and restarting itself randomly. But it doesn't completely turn off, it stays on, but the RGB lights freeze, sound stops coming through, and pressing buttons of keyboard doesn't work.
I thought it was the PSU, replaced it, nope, replaced the GPU, nope. I don't want to end up replacing every part in my pc, I can't just do that.

My specs:
Ryzen 1700
Gtx 1080
16gb G.Skill
Asus prime pro motherboard
250gb SSD
5tb hdd
AX760 corsair PSU

 

[Ralston18]

Use the Reliability Monitor and Event Viewer to look for error codes and warnings that occur just before or at the time of the signal losses and crashes.

Check motherboard and all components closely for some electrical short - loose connection perhaps.

 

[Shirone]

Use the Reliability Monitor and Event Viewer to look for error codes and warnings that occur just before or at the time of the signal losses and crashes.

Check motherboard and all components closely for some electrical short - loose connection perhaps.

I took out every piece of hardware and placed it back in place, it did nothing. Also I noticed, if I'm playing a game or running a benchmark, it WILL not crash. It only crashes while being lightly used like reddit/watching videos/youtube/etc. Another thing is that if I plug in my phone to charge, the mouse begins to act up and slow down, I have to unplug and re-plug the mouse. It happens every time I plug in my phone. Could it be the motherboard?

 

[Ralston18]

Resource conflict perhaps.

Start watching the logs.

Even though you replaced components there is still the possibility of a faulty component or some conflict.

Windows 10 - run the built in troubleshooters.

Likewise use Task Manager to control what is running at any given time.

Watch videos with one of the tools running. Observer what is happening: e.g., disk activity increasing, memory filling up.

Disable unneeded apps and utilities running in the background. You may discover that the crashes end if some particular app is stopped.

Then you know the culprit. And can look for a specific fix. The fix might be as simple as a reinstall.