I have replaced the caps but the problem remain the same... Now I have a nubus card and with this the video output is perfect! I need to replace the onboard vram?

Other problem is the power switch, why my mac not poweroff when i push the back button? It only restart... I only test it without disks, mac need system installed for correct power management? Keyboard on/off not work, and power on take log time (long press of power switch).