colors, random patterns (if all monitors connected to single source GPU), usually denotes video memory corruption. The first thing to look for to rule out is tweaked input cables on the monitors or at the video card and second would be to reseat the video card int PCIe slot. Both of those can cause similar symptoms. If neither is the problem then it points to video memory corruption. Also try driver update that won't hurt either.
(also don't overclock, the couple of extra fps generally isn't worth the stress on your hardware unless cooling is significantly improved)
Thanks for your response, warezme. I checked the cables as well as the seating, so I now believe that the problem may be video memory corruption. I checked for a driver update and there is none. My only trepidation about the belief that it is video memory corruption is that the computer seems to be working perfectly on one monitor. I don't really know how video memory corruption works. Is there a way to test that this is the case, and is there a solution to the problem?