GPU scaling not working at 110Hz

[uhufreak]

Somehow I cannot get the gpu scaling to work with my Qnix 2710 if I'm at 110Hz. At 60Hz everything scales properly.
This not only affects custom resolutions but also such which were already there before the installation of CRU, like 1920x1080 (of course 110Hz was not there in the beginning)
How come Gpu scaling doesnt work at non native refresh rates?
And is it possible to fix this?

I've already tried manuel, lcd standard, lcd reduced and crt standard.

My main resolution is 2560x1440 (110.000Hz LCD standard timings)

another resoltion that does not work is for example: 1600x1200 (cant make it to keep aspect ratio at 110Hz, however it is possible to stretch to fullscreen)
or 1917x1434 (at 110Hz only centered timing is available)

Oh, and there are resolutions for which the gpu scaling works just fine, like 1280x960 @110Hz

Im using a AMD 7950 with the 14.3 beta driver (gonna update soon)
and a QNIX 2710 @110Hz
the cable is a dual link DVI-D

pixel clock is patched and im using cru 1.1.2

any thoughts?