All your data will be preserved but a new system will be installed on the disk.
Once you have finished the archive and install, it's an option at the beginning of the installation process, all you need to do is bring the system software back up to 10.4.11
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I'm on a G5/10.4.11 and had to zap the P-Ram to resolve a USB issue. Afterwards, my screen went to 640x480 resolution, so everything on my screen is too big. However, when I went to the Display preferences to change it back to 1080x780, there were no other options in the menu anymore! I've tried restarting and also "SwitchResX", but no luck. When attempting to start Mac in safemode to see if I could change the settings, it won't do it and the fan starts getting really loud. Otherwise, the Mac itself is working fine with no problems. I hope someone can help me - my other option is to reinstall the system, but I have lots of software/authorizations which will take me a long time to reinstall if I do that. Thanks!

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