follow here and start a clean
https://www.olarila.com/topic/8918-opencore-vanilla-guide-step-by-step-full-dsdt-patched-or-ssdt/
if u have a catalina, prepare ur folder with last bootloader and kexts version
u can ignore it or create one injector with cpufriend for down at 800mhz
https://www.olarila.com/topic/5693-guide-ssdt-with-pikes-pm-script-and-use-with-cpufriend/