I fixed the problem myself :)
Thanks for trying to help me!
Requirements :
Another (Working) Mac (Maybe a HackingTosh will do haven't tried that )
One USB Drive at least 8GB
One or two harddrives (IF your PowerMac G5 doesn't have one already)
What I did :
Made USB with OS X Leopard on it(Via MacBook Air).
Boot from USB with Open Firmware (Looked it up on google)
First 2 times I made the USB it said it could not install third time BINGO!
I have used the same DMG file and USB third time it should work!
Installed OS X 10.5 Leopard (Just follow on-screen instruction it isn't hard at all)
(When it says Less Then One Minute Remaining it takes at LEAST 8 Minutes)
Proof (I added all the DDR2 RAM I had so that is why you see 7 GB DDR2 SDRAM) : http://i.imgur.com/mJCh770.png
Running some programs : http://i.imgur.com/q0VAuJY.png
As I thought this is a perfectly working PowerMac G5 hopefully someone finds this answer useful!
And surprise my DVD drive works (Tested it with some music) but for some reason it just doesn't want to boot off DVD.