Am I wasting my time?

Hello!

I am working on an Power Mac G5 (well 2 actually trying to get one working) the one i am most interested in running is liquid cooled but has no HDD. I got a HDD for in put it in and put a Mac OS 9 disk in the CD drive (starting low then planned to work up) but the problem is when I start the Mac it wont boot from the CD/DVD drive the drive spins up but the system wont access the cd (even when the HDD is unplugged) the screen just flashes the ? and =) folders. Am i doing something wrong? (The HDD can be accessed from another Mac with a firewire connection and has Mac OSX on it but the G5 wont read the HDD either) Is there a mother board failure? The system was $40 (mostly for the video card). Please help. Any assistance will be appreciated!

Thank You!

-B