For the Mac Pro (Early 2008/9), a.k.a. MacPro3,1 In the MacPro3,1, the power supply screws are 2.5mm hex, not T-10. Also, there is a cover plate behind the superdrive that has to be removed (2 phillips screws) to expose the power cable connections and those connectors must be detached and slid under fan before the power supply can be removed.