I have an older 867 G4. I installed Tiger and had some older RAM chips from another G4. I tried them but the Mac didn't boot. Now the Mac fires the power supply, makes a short sor of buzzing sound and the front light goes off and it shuts down. I pressed the reset switch on the motherboard, held down the C key, unplugged the power for a bit etc.
Could I have fried the motherboard with the wrong RAM?