How do I get this Mac G5 up and running ? (boot to OS) A local Goodwill sells Apple hardware at ridiculously low prices, great for a tinkerer like me. I'd missed the Mac mini on sale so I grabbed this Mac Pro looking device thinking it would be an intel running unit. The $25 price tag and wire tie kept me from opening. the cover to confirm and they don''t offer refunds.
When I opened it at home the plastic cover inside had the great big G5 on it and my heart sank. No hard drive or memory. The little sticker started off showing it as a single 1.6. DDR3 or DDR2 or DDr4 memory didn't seem to fit, but I did shoehorn two sticks of 2gb into two slots. There is a 500gb drive attached inside without rails. Both are to test. There is what seems to be t he optical drive still in the front bay.
I haven't figured how to open the  'apparent' optical drive else I'd searched for an old Apple Mac OS dvd to try. Also I'd have. thought I'd get other than a black screen when turning it on.
What do I need to do to just get it booting into an OS ?
Software - You need to get an old OS X install CD, boot from it, and install. Depends a little on the specific Mac you have, but you can check sites like eBay. You can find more info on sites like: https://lowendmac.com/
To open the CD tray - hold the left mouse button on boot - it should pop open for you.
Shoehorning RAM into a slot doesn't sound healthy. If it came with a stick of RAM, take out your new RAM and leave what was there in it, and try booting. Putting in an unknown stick, at least till the box is up and running is going to be another potential headache.