When im playing prey, When i move, I get a line in the center of the screen. Its like a jumble of colors about an inch thick from side to side. It only does it when I move. What can this be.
Sounds like a bad card... Keep an eye on the temps, try different drivers, directx, etc etc. If the problem persists, try just useing a single card, possibly pinpointing the problematic card...
If your card isn't seated properly or simply lifted up you could be seeing this due to moving the mouse and pressing keys with the case on the same surface would feel the slight vibration there. That would be an intermittent condition seen there. If there is problem with the mouse or keyboard with the connectors or cords there could be a slight electromagnetic interference from something unshielded. I've been scratching my head for 2yrs. on a similar circumstance where the swapout of video cards suddenly saw a series of horizontal lines when at the game menu with the new card.
With a new hard drive and another type as well as card on a totally new board the same thing is still seen. I could suspect that your game runs with the cd in the drive? Here I could say a possible scratch on the cd. There you could have either a new interference or fault in settings or hardware. The first card to see this was a AGP Radeon 9550 256mb after swapping out an MSI Microstar 128mb card that ran NVidia drivers. The new card on the new board is also an MSI. I see this in Soldier of Fortune II showing it's not the game at fault here or there.
I had an Msi 9550 radeon. Had no problems. I checked the card. Its installed properly. Im gonna try another game. If it still does it, Im gonna send the card back.
Here I only saw this on one game alone. But that was also seen at the options menu and not during game play. The problem here was seen with not only two different cards but types as well. One thing you could try is disabling "write combining" in the advanced settings. That has been known to cause problems with various games. What game are you seeing this in? Sometimes lowering or disabling some settings in the game itself like anitliasing can be a help. If you still see problems after playing around with a variety of game and card settings ship it back then.