4 Old PowerBook G4s

So I have 4 PowerBook G4s that aren't working right, and was wondering if there is anything I can do. Two have one model of logic board (where there is a plug from the keyboard and a strip that slides into a slot), and two have another (where there is just a plug from the keyboard). For the two with the latter model, one consistently turns on but beeps and startup, with know image going to the screen. The other seems to work sometimes but not consistently turn on. I switched the logic boards, and the beeping logic board consistently turns on still, so the other parts are fine. For the two G4 of the other logic board model, one of them was working alright except for the firewire, until I switched the logic boards between them and switched them back, now that one doesn't turn on consistently. The other one gives me a pink screen with bars after about two minutes of use.

So, has anyone had any experience with these working, but not turning on consistently? They turn on, and when you turn them off you have to wait about an hour before they turn on again.

The turning on and off could be a sign of a faulty power supply. And the beeping is usually caused by either the Ram, or the logic board.

They don't turn on and off. It's that after I turn them on and shut it down, I have to wait an hour or two before it will turn on again.