Step 4 — RAM
Release the tabs on each side of the RAM chip at the same time. These tabs lock the chip in place and releasing them will cause the chip to "pop" up.
Pull the RAM chip out.
Repeat this process if a second RAM chip is installed.
Step 5 — Lower Case
Turn the G4 over.
Remove the eight Phillips screws from the lower case.
Step 6
Using your thumbs, slide the lower case away from you.
The lower case may stick in the front on a tab just above the center of the DVD drive. Be careful as you work the case off, or you may break the thin strip of plastic just above the drive.
Lift the lower case off.