G4 Quicksilver (leopard) wants to restart even if idle

From your description, that's a kernel panic. About 9/10 times its due to a hardware issue, and the remaining 1/10 its due to software. If you've done clean erase & installs every time on those OS' its time to look at what you have connected to the system other than the keyboard and mouse, or if you added any expansion cards. You should also definitely run the Apple Hardware Test. Its on a special partition of the Mac OS X Install Disc 1 that came with the computer originally, and can only be accessed with the option key held down on startup with the disc inserted. The 'D' key shortcut that you sometimes see in reference to the hardware test is for Intel processor Macs. Run it and see what what it reports.

JediMeister said:

From your description, that's a kernel panic. About 9/10 times its due to a hardware issue, and the remaining 1/10 its due to software. If you've done clean erase & installs every time on those OS' its time to look at what you have connected to the system other than the keyboard and mouse, or if you added any expansion cards. You should also definitely run the Apple Hardware Test. Its on a special partition of the Mac OS X Install Disc 1 that came with the computer originally, and can only be accessed with the option key held down on startup with the disc inserted. The 'D' key shortcut that you sometimes see in reference to the hardware test is for Intel processor Macs. Run it and see what what it reports.

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thanx
Didnt know about the option Key for that.
Took it with C-Key but froze after few minutes

G4 Mac's are notorious for having mixed results when running OS X Leopard. A lot of issues tend to be along the lines of the computer freezing at a blue or gray screen after booting. Most of these tend to be fixed by just doing another Erase & Install of the OS. Also when installing, when you get to the "you are ready to install!" screen, look on the bottom left and you'll see a Customize option. Click that and choose not to install things you don't need. There are MANY printer drivers that most people don't use. For instance, I only have the HP drivers installed because I don't use my PowerMac G4 anywhere where there aren't HP printers (namely my home one). Also you should choose not to install any extra localizations (languages) mainly for space saving.

I dont think Leopard on a Quicksilver is a good Idea,as you need a minimum of 2 Gb ram,i would say.
i just put Tiger on my G4's,except the MDD have Leopard on it

Here is any which looks me good for Tiger.
Havent tryed it yet myself
https://forums.macrumors.com/threads/1215904/