Well just about everyone knows that PC fans are great for cheap airflow so I was over on Newegg the other day and came across these watercooled fans for PC boxes and thought it might be a great way to cool down your growbox. Obviously most people's growboxes are larger than a PC case but these things lower PC temps by between 40-50 degrees according to some reviews, so I was thinking it should lower the temps for the average sized box 5-15 degrees if used for intake fan. The thing I'm not sure about is if they could be wired like PC fans with a 12v or other adapter so you could just plug it in. Here are a few relatively cheap ones I found http://www.newegg.com/Product/Product.aspx?Item=N82E16835108095 http://www.newegg.com/Product/Product.aspx?Item=N82E16835186134 Wel let me know your guy's input, I might order one in the future.
Those are water blocks for cpu cooling i don't think those have a use for growing but if you want to overclock your computer your in luck.
Yeah I don't know a lot about them, but I know a thing or two about heat transfer and I don't see how this could be much better than a plain fan except in a small grow box. It would be pretty cool (no pun intended) to use in a mini fridge sized grow box though. Or possibly even modifying a HID hood to mount one of these, to keep the light cooler so it can be placed closer.