Do not use the AF 120s for radiators or heatsinks, they're mad specifically for pushing air through a non resistant object, just like a heatsink or radiator. However, the SP 120s are made specifically for radiators and heatsinks, and Corsair's watercoolers come with a cheaper version of the SP 120s by default. I have an H80i, but I forked out 30$ for the retail SP 120s because they have the coloured rings which accents my rig very nicely, so I can say from personal experience that they are great fans. I have the high performance editions, but I control them with Corsair Link software to run around the RPM of the quiet editions most of the time and ramp them up when I'm doing some crazy overclocking and benching. If you are going to be able to control the fans either with a fan controller or software, I'd recommend getting the high performance versions because it's like getting 2 in 1. You only get the high performance when you want it, otherwise they're quiet as you want them to be.