Question Monitor, Keyboard and Mouse randomly lose connection, All fans on PC still running

Sep 8, 2021
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This is the first system I have built, with secondhand GPU and MOBO.
Specs:
-GPU: EVGA GTX 970
-CPU: i7-6700
-Motherboard: ASUS ROG b250-G
-RAM: 16GB (8x2) Ramaxel DDR4
-Storage: 2TB Hard Drive
-PSU: ROG STRIX 650w
-Display: 144hz AOC 24g2
-Case: Rotanium TG307- with 4x6w RGB fans.

Monitor shows no signal seemingly randomly, sometimes while in a game, sometimes while idle. when this happens my keyboard also seems to turn off and on randomly, (i can see this because it's rgb)
I can also hear audio for a few minutes after the monitor turns off.

I've reinstalled windows, upgraded the PSU (was on a 450w initially), switched cables and monitors.

Nothing seems to work.
sometimes the PC works fine for days without doing this, just then I turned it on, saw the BIOS screen and then it lost connection. ):

very frustrating...
maybe it's worth mentioning that drivereasy says that these drivers need updates and are apparently from 1968?:
Intel(R) 200 series Chipset family LPC controller (b250) - AC28
Intel(R) PCI express Root Port #5 - A294
Intel(R) PCI express Root Port #9 - A298
Intel(R) PMC - A2A1