Leopard would run slow if at all. I've heard of people installing it on the older Macs. I don't think you have the RAM to run Leopard correctly. What do you run, Tiger?, Panther? Jaguar?
It probably would, but not very well. Leopard eats up RAM and it would be slow and unresponsive. I would recommend staying with Tiger on the G3, having both Tiger and Leopard has its advantages. I run Tiger on my iMac and Leopard on my MacBook. It gives me the best of both systems.
"Mac computer with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor 512MB of memory DVD drive for installation 9GB of available disk space Some features require a compatible Internet service provider; fees may apply. Some features require Apple's .Mac service; fees apply."
Note that
Power PC G3 is not listed, and there was never an
iMac G3, with
867MHz or faster processor manufactured.
Apple Rules, no there is no supported way. If you attempted it you would be faced with the following issues:
1. Updates may not work.
2. Kernel panics could happen.
3. Graphic User Interface elements would run slowly if at all.
4. Third party software, and drivers, may not work at all.
5. Insufficient disc space or RAM to do simple multitasking.
In essence, you are proposing to put a jet engine on a horse drawn chariot. You are proposing to make a jalopi out of a machine.
Is it really your intention to exceed the capabilities of the machine and make it work haphazardly if at all? We get enough complaints from people whose specs suggest it should work on their machine. Imagine the complaints trying to run it on a machine that isn't supported. If you do it, take full responsibility for whatever failures happen.
Aww 😟. I guess Apple really wants people to buy those Intel Macs of there's. Hopefully in the future XPostFacto will be updated to support G3 processors for Leopard. I see no reason why it wouldnt be. Remeber when 10.0 dropped support for all the non G3 processors? Yet 10.0-10.2 ran fine on them with XPostFacto.
Make no mistake, XPostfacto was not made by Apple. And even though it allowed booting of older operating systems, it still didn't mean those Macs were necessarily usable. You were still pretty much on your own when using such a system, and couldn't except continuous updates.
It was more of a borrowed time.
And don't forget Leopard will run on an 867 Mhz G4. Those Macs were made 6 years ago!
That's a pretty good length of time for a Mac that basically lost its AppleCare in half as much time.
To expect something that lost its AppleCare in three times as much time sounds a bit excessive.
There are always used and refurbished Mac operating system discs too.
So it isn't like you can't get Tiger or earlier, or Macs that run those systems.