[SOLVED] Computer would randomly turn monitor, keyboard, and mouse off while fans are running ?

[V0rtexx]

So recently I built my brother a PC and at very random times it'll turn off the monitor, keyboard, and mouse while fans/lighting are running as the title stated. But it also displays red blinking lights on the MOBO with a long on RAM and a short on CPU. Afterwards it runs normally if I restart it manually, but it happens again later on. Mostly happens while he's gaming

Also forgot to mention that after the restart, the lights on the fans would default to their color (static red) since we had it RGB before.

A while back I've done a Window's Memory Diagnostic, soon prompting to a message stating a hardware problem, but after reseating the memory in A2/B2, warning went away from diagnosing again but the problem still insists even after putting it in Slot A1/B1 or just one stick of ram in A1.

I've tried running stress tests on the CPU, RAM, and GPU for up to 3 hours and it didn't initiate suspiciously.
So my guess could be RAM, MOBO, or Power Supply but I'm not sure so I need your guy's help.

Specs:
CPU: AMD Ryzen 5 2600x
CPU Cooler: MASTERLIQUID ML240L V2 RGB (Used)
Motherboard: GIGABYTE B450 AORUS M
Memory: Patriot Signature Premium 8 GB (2 x 4 GB) DDR4-2666 MHz
HDD: Seagate Barracuda 1 TB
SSD: Inland Premium 256 GB M.2-2280 NVME
GPU: XFX Radeon RX 560 4 GB
Case: Cooler Master MasterBox Q300L TUF Gaming Alliance Edition
Power Supply: ARESGAME AGV 500 W 80+ Bronze

https://imgur.com/a/eCAJF6s

View: https://imgur.com/a/eCAJF6s

 

[Rit101]

Same issue happening with my pc too. Mouse, Keyboard and Monitor randomly turns off but in my case it happens mostly at startup or at idle and never turned off while gaming. I need to do a reboot to fix it.
I changed PSU and cmos battery still having this issue.
Brother if you find what's causing this issue or any fix, kindly tell me.