I have the ZM80C-HP on my 9500 Pro. The optional fan that Zalman offers mounts on the top of the card as it keeps the heatsink bases cooler. Keeping the heatpipe cool is not the purpose of the heatpipe. The heatpipe transfers heat from the front to the back so you have more surface area. To be honest, though, with no fan I got the core on my 9500 pro up to 410 with stability. A fan might be good to increase life, but it's really not necessary.
Also, you may want to invest in RAMsinks. You'll have to custom cut RAMsinks for the back because the clearance is around 8mm or so. I haven't checked to see if the OCZ copper Ramsinks fit yet. I'll be trying very soon, though.
P.S. The fan WAS very loud, wasn't it?