for PURE alu/copper coolers...

1/ passive cooling
id say aluminium would be better since it dissipates heat better than copper

2/active cooling
copper due to the fact that copper is a better heat conductor but not as good at aluminium at dissipating heat. only thing is.. with a pure copper cooler like the xp-90c, a high powered fan is needed to make it really shine. so depends on how much noise u can tolerate. sadly...weight is also another issue....

and as for copper base and alu fins heatsinks...u do realize that some of the best cpu heatsinks in the world are made that way right??

EDIT: before u turn into hardass ...lemme just say these are personal opinions only..not expert

This post has been edited by mADmAN: Apr 6 2006, 05:15 PM