from the sawtooth to the pre-133mhz bus G4's - these can all be upgraded to Dual 500Mhz cpus I think which u can see on the chart. is the highest 100mhz bus cpu
the only catch is u have to check the uninorth with
http://www.macupdate.com/info.php/id/13551/uninorthasicchecker to get a positive result.. then u know it will accept this dual 500mhz cpu
taking this 100mhz bus cpu type and putting it into a qs would result in it being massively overclocked i think.. which probably isnt a good idea?? (mactron myabe knows more?)
as protoolsleguy pointed out, these pre-133mhz g4's can also take a DA/QS 133mhz cpu as well, if they have voltage wired to the 4th pin, but the cpu runs slightly slower due to bus difference, so the dual 1ghz QS cpu would run as a dual 750mhz? or something liek that? the qs cpus 867, 933, dual 800, + dual 1ghz are all excellent cpus....with 2mb cache but the 733 has NO cache... but remember the DA 733mhz does have cache but only 1mb.. so my reccommendation for devils advisor would be to find one of these qs cpus.. 867,933 or dual 800 or dual 1ghz.. find me a dual 1ghz;)
and of course any Quicksilver CPU can be easily transplanted into any Digital Audio model (and vice versa) as they are basically the same motherboard config.. which means u can take a 1ghz dual QS cpu and put it into a 466 Mhz Digital Audio... and boom!!! major gains.. from 314 geekbench to 854..biggest jump in stock cpu swap.. the ghz remaines the same because they are both 133mhz bus systems and no extra voltage is required .. u could also put any digital audio cpu into any quicksilver... the only drawback is these machines only take 1.5gb of ram
another thing to notice i think is that the DA/QS systems require 133mhz Sdram..
to match its bus speed
but..we have alot of this information already posted here on old threads from fall 2013
below ive attached an image of the dual 500mhz cpu on a g4 motherboard
u can see it does not interfere with the ide interface.. which adding a QS/DA cpu onto a pre-agp g4 would require...
it would appear someone has already done this as if IIRC the sawtooth is the only board that has an internal firewire port
and this internal port was taken away for the "mystic"/"gigabit" models which originally featured this dual 500mhz cpu