Apple Mac Pro 4,1 2009 A1289 CPU Tray 2 x 2.66 GHz Quad Core Intel Xeon X5550
This is not compatible with the 2010 / 2012 A1289 as the fans go nuts. CPU Tray 2 x 2.66 GHz Quad Core Xeon X5550. Apple Mac Pro "Eight Core" 2.66 (2009/Nehalem). Apple Mac Pro 4,1. This is non-negotiable.