I even had a silencer 3 on a X800Pro.
it cooled better then the original HSF.



if it's on the box, it should work.

on the XT version I have the ATi silencer 5, works great in combination with ATiTool.
fanspeed is regulated, .....

I use Chill Vent.:)
And, I have two silencers not being used.:D
If the silencer would give me more; don't you think I'd be using them to brag about? ;)

Now, if I use both CV and Silencer I still get a couple C's lower but it varies with cards I believe.