Dunno mate I just have a box full - I know there's some 800/900s in there but there's very little audible difference but better cooling by the "1300/1400" I was using. 1400 was just what the RPM-meter told me. hdfreedom - I saw them and tried pinching but nothing would move. I looked for screws but there were none and I didn't take a pair of plyers too it because I didn't want to break it. Good to know though! It's still a recommended HsF regardless I would personally probably get the Zerotherm because of the price and I'm never needing "ultimate" performance.