Dude, get the ZM80D if you haven't installed the C already! It comes w/ RAMsinks, too.
I have the ZM80C, and it works, but my 5900XT gives it a good run even with a fan (max 92C--stock coolers generally don't get much above 75).
If I'd known the D would come out 8 days after I got my C, I'd have waited

. I may still get the D if things get too hot (and with the Georgia summer, they just might get that hot). Be warned: have spare heatsink compound around, use a good screwdriver to get the plates on TIGHT, and be careful. It's a PITA to install the first time. Even with the manual, there's a learning curve.
Most people you'll find use the VGA Silencer. But like choosing Thermalright for a heatsink, I want to do the fan part, thank-you-very-much. Aerocool has a new one out, but while it probably performs well, it won't work in a desktop, where the Zalmans work in all but one case that I know of (the new Lian-Li).