Question PC boots up but theres no display after changing the usage of ram.

[rezaka16]

My friend's pc boots up but theres no display after changing the usage of ram. Any advices you guys can give me? He has 16 gbs of ram but today he noticed that only 7.97 out of those 16 were usable, that happens for the first time, before there were 16 usable. He tried to change the usage of ram from mconfig, clicked start - boot - advanced. He unticked maximum memory on that tab too, and after a restart, there's no display.

 

[rgd1101]

full system spec? include make and model of the psu

no bios screen?

 

[rezaka16]

gigabyte r9 390 8gb, ryzen 5 2600x, 16gb,psu zalman 700W ZM700-LEII