Hello FlapFlapRooRoo. I do not have Sierra on my system. I have here a Q6600 processor, and it does not support Sierra. I am already thinking on a upgrade to a compatible quad core processor, but not for now. So, about Sierra, I can not help! I know almost nothing about its nuances. Sorry. Try to boot with -v option and see if the kexts are beeing loaded; and if present, what kind of error is beeing showed! Good luck!