My HP a6700y is about 4 years old and now it won't turn on. The fans turn on but there is nothing on the display. The power supply light is solid ON. I tried unplugging all the components individually - no difference. I unplugged all the RAM (4x1GB), then reinstalled each one individually - no difference. I spoke to one tech and he thought it might be the on-board graphics processor. I think I need a new motherboard but I'm not sure. Can someone help me diagnose further? Help!