I don't see the need to right now because it is actually running pretty cool. It feels similar to a vid card under load. I have good air flow in the case and a 120cfm fan is blowing directly at my cards.
Iirc, BLinux stated somewhere in this thread that OCNers are unnecessarily modding these cards to run overly cool and that the servers that these are being pulled from have inadequate airflow.
I'll try running it with a small fan screwed onto the heatsink. I'm curious because I'm planning on taking out my xfire and running another perc5 in an adjacent slot.