I got the white screen of death and too my mid 2011 27" imac with optional 2GB graphics card to service. Techs diagnosed failed graphics card. Apple care replaced it. Got repaired mac it home and screen started to flicker, went to solid color pastel pinstripe screen, then to a lovely kaliedscope pattern, and white screen of death again upon power off/on. This time techs diagnose a failed LCD. So, now they ordered a replacement LCD. Could the techs be looking at the wrong causes? Logic board? Software issues? Have there been other GPU / LCD failures? Could these be related failures? I always use this mac powering a second display. Tech said that maybe my color calibration display settings were involved (that sounds like BS to me). Ideas?