switching startup disk between computers

You can only do that by booting one of them in "FireWire target disk mode".

For instance:
You want to boot the Rev A. G5 off the internal disk of the Dual 2.0:
- Reboot the dual 2.0, and press the "T" straight after thet StartUp Chime is heard.
- wait till the display gets blue, and a yellow FireWire symbol appears.
- Release the "T" key, and the Dual 2.0 is now in FireWire Target disk mode, so it will act as any other External FireWire drive.

- Now connect the two G5s with a FireWire cable (preferrably a FW 800 cable if you have one).
The drive(s) of the Dual 2.0 GHz should appear on the desktop of the Single 1.6 as external FW drives.

Now to boot the 1.6 off the Dual 2.0 Mac:
- You can alter the "StartUp Disk", in the System Prefs of the 1.6 G5. But this action requires altering back again (or resetting PRAM) after you have finished booting off the 'other" Mac. So I would:
- Startup (or reboot) the 1.6 GHz G5, and press the <ALT> key.
- Hold until you get a blue background screen on this Mac.
- This Mac will now scan all available startup volumes (optical drives, internal disks, external FW disks, NetBoot Server) - Can take 1 minute to complete... don't rush it.
- The Dual G5's disks should also appear.
- Select this volume and there ya go.

Want the other way round?
Vice versa

Have fun

 

robotjustin, did you mean physically replacing the internal disk in the 2.0 with the one already in the 1.6? That should be fine.

However, I recommend using MacsRgr8's method instead. This will run a little app for you that will transfer all of your settings over to the new Mac and it'll mean you won't need to take either machine apart.