Yeah those little fans I cant even feel the air from them even when their not on a rad.....They sold them as 47cfm and they are the LED fans so I don't know either way its amazing to me that they worked at all...I'd say the 69cfm and up 120x38mm fans are great for this rad...
EDIT: I just found out what the wattage rating is on these bad boys..No wonder they cool even with those little fans...480 GTX Wattage Rating
Well I e-mailed Hardware Labs to find out the wattage rating for the 480 GTX..I told them I was going to have a 437W TEC in my loop and I wanted to add another 188W GPU also...I told them I had 8-100+ cfm fans on it in a push-pull...Their answer amazed me frankly, I've been hearing that it was a 1800W rad which I thought was a lot...This is what they rate this rad for in stealth mode, in other words with quiet fans.....Good to know I do want to add a Swifty MC60 TEC block...
The GTX 480 would be more than adequate to handle that.
Its actually rated for 2200W conservatively in stealth mode operation. But its fairly capable of dissipating far more than that depending on the fans used.
I do hope this helps.