no signal on monitor

Anyone can help me? I've been having the same PC problem, my setup boots up to the windows desktop, and randomly having a black screen, while the system unit is still on. It's &&^&^$^ absurd, since I've tried to record how long my pc last before having the problem, and it goes from 18 minutes, to 4, to even 55 seconds after the windows desktop appears. I'm recording the time as the windows desktop appears.

what should i do?

Specs of the PC:

Ryzen 3 3100, Gigabyte B450M DS3H V2, Sapphire Nitro+ RX570 4GB OC + 16GB of RAM (8×2) Avexir Core 2 + 128GB M.2 SATA SSD Western Digital + DeepCool DE500

*we've tested the GPU and no, it's not.

**we've tested the PSU, and so far, even with a Zalman 850 watt 80+ bronze PSU, the $@$* it happens all over again.

***reseated the GPU and RAM, done with bios update and reset, and CMOS too, it still happens. $@$*.

This is really frustrating for me.

Please, do help.