FC6 on iMac G5 -- black screen, loud fan

Hello all usenet!

Yesterday I tried to install FC6 on my iMac G5.  I
downloaded and
burned the DVD iso to a disc and booted to it.  After I hit
enter I can
see some things being done on the screen, but it immediately
turns
black and stays there for about 30 seconds.  After 30
seconds of black,
the iMac fan(s) gets very loud and the screen continues to
show
nothing.  I can only force a reboot.  I've tried the default
boot
(typing in nothing at the very first prompt) and "linux
acpi=off".  I
haven't tried "text" but I will today.

Specs for iMac:
1.9 GHz G5 (3.0)
512 MB RAM
ATI Radeon X600 Pro PCI 128 MB (chipset ATY,RV370)
17"

Let me know what I'm doing wrong if you have any ideas. 
Thanks.

-Pete

"linux text" doesn't work either.