The two machines under my desk are fitted with ASUS HS7850 graphics cards. This one is fine, as it always has been. The other machine has a problem. About a third of the display is covered with small marks. The marks consist of spots placed at the corners of a rhombus. The spots are generally light coloured, sometimes flashing. They do not appear "fixed", ie. they can be forced to move about by dragging a window or similar. The machine has been power cycled, no change. Today, I reloaded the graphics driver from the DVD, booted, and no change. The machine runs 24/7 crunching BOINC work. Before I noticed this problem, the GPU was in use by a couple of the projects in the machines science portfolio, ie. Einstein and Milky Way. I have, since seeing the issue, disabled those projects from getting new work. Any ideas of things to try before replacinging the card?