The ASUS CPU SUPPORT list for the P5k DELUXE
http://support.asus.com/cpusupport/c...Language=en-us
shows that the Q6600 Stepping B3 is supported in BIOS 202,
and that the Q6600 Stepping G0 is supported in BIOS 0404.

Has anyone with an BIOS older than 0404 gotten a
G0 stepping Q6600 and been able to boot / use the BIOS /
flash the BIOS to a newer version that claims to support
the CPU stepping?

What errors / problems did you encounter in using a
G0 Q6600 with BIOS before 0404? What version did you
try?

I'm getting a G0 Q6600 and already have the Motherboard,
with an old BIOS (presumably), I have no other CPU
for this board, and don't know for sure if I'll be OK
plugging the G0 into the board which probably has
0202 or some other old version of BIOS.

I would NOT want it to fail to flash, or to
overvolt / underdvolt / overclock or otherwise use bad
settings for the G0 due to it not recognizing it properly.