Fans go crazy, There are two SMC chips on MacPro. One of them is on the backplate and the other one is on the cpu tray. In order to run MacPro smoothly, SMC chips needs to be synced upon boot. If they can not sync then the fans go crazy. You need to swap the TC4424P SMC chip on the 2009 cpu tray with the TC4424P SMC chip on the 2010-2012 cpu tray. This job needs top soldering skills!!. If you manage to do that then the SMC chips will be in sync and the MacPro will run smoothly. I did it with my 2009 MacPro 4.1 with 2009 4 core cpu and upgraded it to a 2009 MacPro 5.1 with 2012 12 core cpu. Also after the job done, I soldered remaining SMC from the 2012 cpu tray to my 2009 cpu tray with no SMC on it. After that it was a perfectly working 2012 cpu tray. Gave the tray to a friend who needs a 2012 cpu tray for his 2012 MacPro. He still uses that and I still use mine. You just need to find someone with top soldering skills if you don’t have any.