The good news is that Mac OS X 10.5 Leopard seems to be able to run on any Mac with AGP graphics built around a G4 processor – and even on the 2000 Pismo PowerBook (the first PowerBook with AGP graphics) as long as it has a G4 upgrade.

Mac Os X Leopard For Ibook G4 Specs
Apple Ibook G4
Mac Ibook G4 Specs

Mac Os X Leopard For Ibook G4 Specs

The bad news is that the Leopard installer refuses to let you install it on any Mac slower than 867 MHz. That includes the dual 800 MHz Power Mac G4 as well as Digital Audio and other G4 Power Macs that have been upgraded with processors past the 867 MHz mark.

The good news is that there are ways to get around the installer. We’re getting more field reports of successful “unsupported” installations all the time, and most (but not all) features of Leopard seem to work on older, slower G4 Macs.

There are two ways of getting around installer limitations. The most common one thus far requires that you have a supported Mac. For those who don’t, it’s possible to hack the installer so it will run on slower Macs or to fake out the Leopard installer using Open Firmware (a huge thanks to Dylan McDermond for sharing this technique).

UPDATE: The folks at iCode have taken the information from this article and used it to create LeopardAssist, a free program that automates this process and eliminates the need to fiddle with OpenFirware on your own.

The bad news is that some third-party additions to the System can prevent Leopard from booting – Unsanity’s Application Enhancer (APE) tops the list of add-ons – so you should make sure all of your software is up-to-date and may want to (or need to) disable System add-ons before installing Leopard.

Executive Summary

Unsupported Macs that Can Run Leopard

Apple provides no support for Mac OS 9/Classic applications on any Intel-based Macs at all or on PowerPC-based Macs running Mac OS X 10.5 'Leopard'. Please particularly be mindful of asterisks, as these note that a system is capable of running Mac OS X 10.5 'Leopard' but the 'Classic Environment' is only supported when running Mac OS X 10.4.11.

Then I installed Leopard from my G4 Dual 1.45 GHz PowerMac on the iBook's volume. It worked flawlessly. After I restarted the iBook System Update also run without any troubles. 10.5.5 and all current updates are installed and the iBook is working like a charm. Explore the world of Mac. Check out MacBook Pro, iMac Pro, MacBook Air, iMac, and more. Visit the Apple site to learn, buy, and get support. The PowerBook G4 is the last generation of the PowerBook series, and was succeeded by the Intel-powered MacBook Pro line in the first half of 2006. The latest version of OS X that any PowerBook G4 can run is Mac OS X Leopard, released in 2007.

Pismo PowerBook G3 with a G4 upgrade
Sawtooth/AGP Power Mac G4
Mystic/Gigabit Ethernet Power Mac G4
Power Mac G4 Cube
Digital Audio Power Mac G4, including one dual 533 MHz model
Quicksilver Power Mac G4
Quicksilver 2002 Power Mac G4
PowerBook G4/400 and 500 MHz, slow graphics
PowerBook G4/550 and 667 MHz (VGA), better graphics
PowerBook G4/667 and 800 MHz (DVI)
700-800 MHz G4 iMacs
700-800 MHz eMacs
800 MHz iBook G4

Unsupported G4 Macs that Can’t Run Leopard

one dual 533 MHz Digital Audio Power Mac G4, may be due to old firmware
one Cube failure, which could be due to old firmware
two users have failed to get Leopard running on Blue & White Power Mac G3s with G4 upgrades

Cautions

reports of white screen after sleep on G4 iMacs with Nvidia GeForce 2 and GeForce 4 graphics (reportedly solved with OS X 10.5.2 and Leopard Graphics Update 1.0)
GeForce 6200 AGP video card may add up to 5 minutes to startup time

Limitations of Leopard on Slower Macs

Before you install Leopard, you should know that some features may not work on older, unsupported hardware. One of the earliest unsupported installations was reported on Engadget.

Thomas Ricker has an AGP Power Mac G4 (a.k.a. Sawtooth) with 512 MB of RAM and a 1 GHz processor upgrade. He did a clean installation on a freshly wiped 20 GB hard drive, and he reports that performance feels comparable to Mac OS X 10.4 Tiger, which jibes with most of the other reports we’ve heard.

Ricker reports on some things that don’t work on his 1999 Power Mac G4:

Time Machine: It runs. It does backup. But you can’t get backed up files back, at least not with the older, unsupported video card in his computer. Time Machine appears to require Core Animation.
DVD Player: No luck, not even with a better SuperDrive installed. Again, possibly due to an older, unsupported video card.
Front Row: It appears that the program is running, but you can’t see anything on the screen, making it useless. Once again, probably because the video card doesn’t support Core Graphics.

Failing DVD Player, Ricker attempted to run VLC 0.8.6c, only to discover it dropping about 25% of frames. Again, a supported video card might fix this. The stock card in AGP Power Macs was the ATI Rage 128 or 128 Pro with 16 MB of VRAM.

Low Cost Core Graphics Video Cards

There are three relatively affordable options for Power Mac G4 users (not counting the PCI Graphics model): Nvidia GeForce 6300 and ATI Radeon 9700 and 9800 Pro. Applemacanix buys PC versions of these cards, flashes them for use on the Mac, and sells them via eBay.

Of the three cards, the Radeon 9700 Pro ($109 in 2007) looks to be the best value, as the 9800 Pro ($149) isn’t any faster and the GeForce 6300 ($99) is considered quite a bit slower. The benefits of the Nvidia card include no cooling fan, low power consumption, and no need for an auxiliary power connector.

Adding one of these cards to an AGP, Mystic, or Digital Audio Power Mac G4 could be all that’s needed for Time Machine, DVD Player, and Front Row to function. We will update this article if we receive field reports confirming or disproving this.

Hacking the Installer

If you don’t have access to a supported Mac, the first alternative was to hack the installer. You can do this on a dedicated hard drive or by burning a DVD, in which case you’ll need a Mac with a SuperDrive. Mac Rumors has posted instructions, which we’re summarizing here:

Install DarwinPorts [archive link] and restart your Mac.
Make a sparse disk image of the Leopard install DVD. Mac Rumors suggests Carbon Copy Cloner 3 as the best tool for this, but Disk Utility will do as well.
Open the Terminal and follow the posted instructions to the letter. You will either be modifying the code by choosing a minimum CPU speed below 867 MHz (300 MHz is a safe bet, as the slowest G4 systems ran at 350 MHz) or by making it only work on Macs slower than 867 MHz. Either choice is fine.
Burn the hacked disc image to a blank dual-layer DVD-R or DVD+R.
Run the installer to see if it works.

Apple Ibook G4

The Leopard installer is over 6.5 GB in size, so you need to use a dual-layer DVD unless you’re willing to modify the disk image before burning the DVD. If you don’t have a dual-layer DVD burner, Lionel Faleiro has posted directions for stripping Developer Tools, languages you will never use, etc. and making the Leopard installer small enough to burn to a single-layer DVD.

One reader has also reported success modifying the Open Firmware to report a CPU speed higher than 866 MHz. This is a temporary modification that resets itself the next time you restart your Mac.

Another reader has reported success using a modified installer and NetBoot.

Using a Supported Mac

If you have access to a supported Mac, you can avoid all that Terminal work.

Because Leopard is Apple’s first universal binary operating system, you can create a bootable disk from either a PowerPC or Intel-based Mac.

You have some options here. If you have a Power Mac G4, you can install a second Ultra ATA hard drive inside the computer, install Leopard, and then transplant the drive to your older Power Mac G4, iMac G4, or eMac (which is a tricky beast).

If you have an external FireWire hard drive, you can install Leopard to any partition from a PowerPC Mac. If you’re using an Intel-based Mac, you’ll want to create at least two partitions: one for the GUID partition that the Intel Macs like to boot from and an HFS+ partition that you’ll clone the installation to.

Once you’ve installed Leopard to the FireWire hard drive, move it to your unsupported Mac, choose it as your startup volume, and