Question does not show resolution

[Radovan Andjelic]

Hello,
So my friend asked me why does it not show his resolution witch is 1600x900 (don't ask me). Specs:
Mb: msi h61m-p20 g3
Cpu i5 2500k
Gpu asus rx 570 8gb oc
16 gb hyperfury ddr3

When he enters his old graphics card gtx 750 it shows that wierd resolution witch he needs.
Can anyone help me with this?
And if you need any further information please let me know.

 

[rgd1101]

what connection is he using? hdmi/dp/vga? using adapter ? windows id the monitor of just generic