G4 won't recognize any hardrives, even new one?

[onelane]

I have an older G4, 1st gen AGP 400mhz. i had my main hard drive go bad about 6 months ago, i replaced it and it worked for about 6 months, before one day it locked up, and upon reboot the computer would not recognize either of the hard drives previously installed. i thought maybe it was bad luck and the drives went down or that the new one died, and i dont think the other one had an OS on it. So i bought a new western digital and installed it and when i boot from osx 10.4 system disc it still does not see the new drive? the jumpers are set right, the drive gets power and spins up? i switched the ata cable and that didnt help? is it possible that something on the motherboard fried and is not reading the drives? the ata cable is obviously working for the dvd-ram drive that i boot from cd on? perhaps something is shorting on the motherboard that caused the other drives to fail, cause i think i've lost 2 in the last year or so?

any suggestions would be greatly appreciated. i've been on macs for 15 years, and am comfortable swapping hard drives and that type of stuff, but things deeper in the operating system like bios stuff is a bit over my head.