Iused some cat5, I tried mini coax, I bought a 5mtr extension, I bout 3 2mtrs extension, and I tried all combinations.
Some work better than others, cat5 works ok upto a few mtrs, 2 of the 3mtr extensiojns worked fine, 1 is a pig, the 5 mtr extension was a little better than cat5 at 3 mtrs
I stuck with the 5mtr cable, worked ok.
only answer is to play witha few cables because what works fine on 1 monitor/gfx card can be poor on a different machine, its madness.
get a few cheap ones off ebay and play.