Noctua more recently released a 2011-specific D14; the D14 for 1155 worked with 2011 but only after ordering a separate adapter bracket or something straight from Noctua. I guess 2011 socket users got a little tired of having to do this, so now there are separate D14's being sold - one specifically for 2011, and the other one for 1155, 1156, etc.