I have stumbled upon an iMac G4:

looks like this

Upon booting it has a series of user account to which I have no idea what the password might be. Obviously a reinstall is in order.

Which OSes will work and, more to the point, which will work well?

  • 1
    If you want to reset the root password, directions are at askdavetaylor.com/…. If stumbling upon means you found one it might help you locate the owner. Of course use your own moral judgement to determine if you should do this or just wipe it. Commented Oct 1, 2009 at 22:37
  • You cannot put intel based x86 systems on a g4 as you can only if it is amd or intel based hardware. I believe most maybe not all Linux related systems are based on x86 compatible os only.
    – user120387
    Commented Feb 27, 2012 at 21:52
  • @JustinDearing makes you think if it will be moral in the future to break encryption/logins for the sake of finding historical data. If you want to see what's on disk and FileVault wasn't used though, just use a Linux liveCD.
    – Hawken
    Commented May 28, 2012 at 16:40

3 Answers 3


10.5 is the last PowerPC compatible mac os. That is the max OS supported. I believe it wants a 866mhz G4 or better and a DVD drive, but it could potentialy work on slightly slower machines. 10.5.8 is the most current version.

Now I had it in on a 933mhz g4 tower and I found it too be on the edge for acceptable use. It would depend on which imac version you had to further know what your user experience would be like. I think it is ok to use as long as you turn off some of the visual effects to speed things up (dock magnification, transitions, etc.)


Apple states the following basic Leopard system requirements, although, for some specific applications and actions (such as iChat backdrops) an Intel processor is required:[51]

  • Processor must be any Intel, PowerPC G5 or G4 (867 MHz and faster)
  • DVD drive (for installation of the operating system)
  • At least 512 MB of RAM (additional RAM (1 GB) is recommended for development purposes)
  • At least 9 GB of disk space available.

Leopard’s retail version was not released in separate versions for each type of processor, but instead consisted of one universal release that could run on both PowerPC and Intel processors.[32] Leopard drops official support for slower G4 and all G3 processors.[51] Because all new Macs use Intel processors, the versions of Leopard shipped with them are Intel only.

  • I have a working Mac OS X 10.5.8 on a iBook G4 933MHz and it performs better than Mac OS X 10.4.11. Commented Dec 7, 2009 at 14:19

Ofcourse it will run Mac OS X, but you can also install Linux on it. Debian or YellowDog Linux would probably work quite nicely, Ubuntu seems to have some problems and PowerPC isn't officiallly supported by Ubuntu anymore. I wouldn't be suprised if FreeBSD would also run on it.

  • 1
    This is of course is also an option as an alternative to the mac os.
    – Troggy
    Commented Oct 1, 2009 at 22:23
  • Don't forget Arch.
    – Jeremy L
    Commented Oct 1, 2009 at 22:46

OS 10.5 should be perfectly fine on a G4, although sometimes things like speech recognition can stumble a bit. I've seen this on a G4 power-book so I assume an iMac would fare even better

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