Accidently G5 upgraded to 10.5.8

Hello, JLvanCSS.

The gray-label reinstall discs are machine specific and will say what Mac they are for; iMac, Power Mac, Mac mini.

The reinstall process should be as easy as inserting the disc in the drive, label facing you, and then rebooting.

When rebooting, immediately press and hold the C key. Then follow the on screen prompts.

Does the Mac show the disk on the desktop when you insert it?

IIRC, some reinstalls begin by clicking the disk and launching the installer inside, then following the prompts. (It's been a long time! 🙂)

Oh yes. I do recall the black install discs. I thought those were retail discs.

Regardless... so you get the process started but it doesn't move through to completion. I understand.

From MacTracker:

The Power Mac G5 Dual 2.0 GHz shipped with Mac OS X 10.4 Tiger. It won't boot to 10.3 Panther.

Mac Plus was my first Mac. 🥰

You can't install an older system over a later system: you will have to erase the disk first. Alternatives are to install on an eternal disk, or you might be able to partition the disk and install Panther on that - then you'd be able to boot into either: obviously you'd need enough space to do this.

Otherwise you'll need to back up all your data on an external disk before erasing the internal disk and installing Panther.

Following from D.I.Johnson's post above, I assumed you originally had Panther running on your Mac? If you didn't, then it may be the case that your Mac can't run it anyway. You can't intall a system on a Mac older than the one it shipped with.

May I ask, why Panther? It's ancient and isn't going to work at all well in the modern environment. Web browing will be nearly impossible. Mind you, even 10.5 is going to be pretty limited.

Follow up -

However, the 2004 G5 Dual 2.0 GHZ should boot to Panther.

And +1 to @Roger Wilmut1's post.

EDIT - I still have that Mac Plus! 😍

Good times! 😁