Hey, again Yes I got this same exact issue with asus 290x DCII and GTX 960
Freesync from monitor menu, only way to get 75hz and these pixel stripes:
Freesync mode OFF from monitor menu vs ON:
Sorry for crappy video (nexus 5) and made a little mistake with wrong monitor tab..:
290x, G3258, 16gb memory,z97 and Win 8.1 64bit:
Usign this cable: http://www.deltaco.eu/en/product/(DP-1020-K)/Deltaco-DP-1020---DisplayPort-cable---DisplayPort-(M)---DisplayPort-(M)---2-m---black/
That cable works just fine with my new "used" ROG swift 144hz with g-sync