http://www.reefcentral.com/forums/sh...&postcount=233
This link is to a post that gives a lot of info about the variety of leds fixtures.
And I have to disagree with one think Michael said above, most led fixtures these days run pretty cool. In fact my Reef Breeders Photon V2 has fans that are thermally controlled. The fixture doesn't even get warm until you start to run it at 75% of capacity or more. I run my blues at 90% and whites at 40%, the fixture is hardly more than room temp and the fans don't even come on!