http://www.everymac.com/systems/apple/imac/specs/imac_g5_1.8_17_als.html My girlfriend has a white iMac G5 1.8 Ghz with 17 inch screen. That machine is running 10.5.8 and has always worked well. Yesterday at startup the desktop no longer appeared. The screen remained blue and next to the mouse appeared a small square with black vertical stripes. Is the graphics card broken or is it the motherboard? Or something else? PRAM reset does not help, and after a while the fans start to run faster and faster. Who knows what to do? TIA.