Just signed up to say that I am getting the horizontal lines too, as Dr Fish has said and as I am finding, it only appears when G-Sync is on, it also gets worse the lower the FPS I have, playing something like Star Citizen's Arena Commander where the FPS is on the lowish side (40s) creates noticeable lines which are very distracting! While playing something like Planetside 2 where I can get a consistent 80 - 100 FPS means it is very hard to spot - but I'm pretty sure it is still there. It's sad because apart from that, the monitor is perfect, the refresh rate is excellent, the screen quality is great and I have very low BLB (at least compared to my Dell U3415W). Now I'm stuck in a dilemma of what to do - I have a good sample apart from the lines but now that I've noticed it, I can't ignore it. So what do I do, if I RMA'd it can it be fixed (We don't yet know whether this is general problem for all X34's or not), or should I just cut my losses and send it back? Any thoughts would be great, If people want I can give my own pics of the lines, so long as my phone camera can pick them up.