Ok so I just got my video card working (XFX Radeon HD 7850) and I opened Minecraft to do a FPS Test. I noticed some random barely visible lines on my screen and in game. I don't really know what the problem is because I tried tightening my Hdmi to VGA adapter thing (Or whatever it's called lol) but that didn't really work. It's only with Minecraft so that's probably not the problem.
Are these the only games that you play? I am thinking you have an outdated driver. If you installed the driver from the CD that came with the 7850, the driver on CD is probably outdated. What you want to do is go to your manufacturer's website and look up the latest driver for the 7850 they provide. Hope this helped!
I just downloaded the driver from the website earlier, so I didn't use the CD. It might actually be that the VGA adapter is loose because it keeps disconnecting but the twist things on the VGA adapter seem to not be tightening all of the way. Maybe it barely comes loose and that is the problem.
So I think it's called screen tearing. I enabled VSync in Minecraft and it stopped but now my FPS is like 40-55 instead of 90-150, so I don't want to keep it on. Is there any way of stopping screen tearing other than using vsync?