Displayrefresh and r_mode?

Hello all,

I have a Iiyama vision master pro 454 and the correct drivers.

My resolution in windows was 1280x1024 @ 100 Hz
So no problem for me to play r_mode 6 @ r_displayrefresh 100 in ET

Now i changed my monitor resolution to 120 Hz but when I wanna play ET with r_mode 6 @ r_displayrefresh 120 my screen crops and the edges are bending.

I can play r_mode 8 @ r_displayrefresh 120 without a problem (same resolution as in Windows) but why isn't it possible to get this refreshrate in r_mode 6??

Anyone knows a solution for my prob?
Thx in advance!

Rfki