i have two power mac G5's, a dual 2.7 GHz (Early 2005 - purchase jun 2005) and a quad 2.5 GHz (Late 2005 - purchase jan 2006),

both max ram, HD : 2 x 1 TB, in use on daily base

The quad is better than the dual, less noisy, and a lot faster (40 to 70%)

if you buy one second hand, inspect the cooling unit for traces of leaks (you have to remove the alu shield)

if there are no traces, download iStat pro (widget)

check the speed op the CPU A pump & CPU B pump at start up, they always must have an equal value rpm (1250 rpm at start)

run some apps ( photoshop with a big file and run some filters, or videorendering, ...),

a higher value, but equal

most stable mac os : 10.4.11

in energy saver, tab options > Processor speed > Highest

with this option selected, the fans starts immediately after boot

the sound level is low, with less peaks or peaks with shorter duration

HD's : never in sleep mode

if you have to move the G5, let it always upright

i always shut down de G5's at the end of the day

(some people say you must leave the computer on to avoid leaks, i never seen a problem with daily shut down/start up )

for best performances, max ram (use apple compatible ram - and test it - hardware test) and a huge amount of free hard space

page-ins/outs , on my G5's : the page-outs ever stays = 0

(apps : 3D rendering ArchiCAD, Cinema 4D, Final Cut Pro - DVD Studio Pro, Photoshop, Cleaner 6, Filemaker - huge databases... )



don't put the G5 on the floor,

clean the inside regularly with a vacuum cleaner