My monitor is no spring chicken, but its worked perfect up until about a day ago. It is an LCD, the Dell E207WFP, about three years old. All of a sudden I am recognizing on dark backgrounds diagonal waves all on my LCD display. I thought my video card went bad or it was a driver problem, so I updated it. Still the same thing. I plugged the VGA into the standard on-board and still waves. I removed all magnets and speakers, and STILL waves! Its so annoying please give me any tips, oh and I am running windows 7. Should I jump for a new monitor?
It is likely that it is either the cable has gone bad or that your monitor is over the hill so to speak. It could be the lcd power inverter has gone bad or the psu isn't providing enough power any more to the lcd. So check the cable and if no improvement then I don't know what else there is to try as you already ruled out the gpu being the problem.