On an AMD 64 (mult locked like intel) its pretty much the same deal.... Only the FX chips and the mobile chips are multi unlocked these days for us AMDers. As always good ram helps. It seems AMD 64 loves having low latency mem timings as well - lots of peeps talk about going for the 1T overclock. don't ask me that one
If you want a fast system with a fanless cpu ( ie limited clocking potential) then i guess optimising areas other than the box are gonna be pretty important, so a large dollop of good ram and a fast HD aint gonna go amiss.
Whats the box for Myth?