it may happen have to respect all the steps. Make sure that you have the MacPro EFI Firmware Update 1.5 package from Apple OPEN (just Open in the background but the .pkg file not clicked) then run the Mac Pro 2009-2010 firmware Tool hrutkay’s video is perfect: https://youtu.be/nwxxjmthRbs
hello i have also questions about problems with the cpus not detected, the no-booting mac :-( have to check if the processors are already working have to check if no pins are bent on the socket under a cpu i found that.. https://www.imore.com/how-upgrade-your-older-mac-pro-cpu?fbclid=IwAR0cgwcNLZmprF5dVo-XFmdwa8SFngDFxSPCixHdDk-cHO_bfaevcSxT1Ok 1) the black connectors of the heatsinkers , have to be reseated (a little bit out of their original position). to be perfectly connected. 2) doing this tricky operation… NEVER OVERTIGHTEN the springscrews when seating back the sinkers. cross pattern. never press on the top of the sinker. count the number of rotations before (when removing the sinkers), note them, and reproduce them with care 3) have to respect the difference of thickness of a delidded cpu and a lidded one. (3mm or 5mm), this layer…. with 3 or 3 washers? 5mm thickness of thermal strip ? he removed the original pink layer.