I just bought an Airport Extreme card and installed it in my PowerPC G5, but nothing happens. The machine will not boot up. But when I take the card out, it does fine.

What info do you need to know before you can begin to help? I can't find out which version of G5 it is.

All I have is the info given on "About this Mac"
1.8Gb PowerPC G5 9.1
1 Gb DDR SDRam
Serial number: G8521E1QQYU

From this, how do I tell which G5 I have?
I can do all things through Christ which strengtheneth me. Philippians 4:13