What tool are you using too see cpu temps ? I can see the overall temp but core temp and other tools arnt showing the core temps don't know if the tools arnt updated to work with the cpu yet or if I've got a problem on my end.
My idle temp is about the same at 45C-50c I'm with the stock cooler but I wasn't too bothered as I'll be sticking it in my water loop when I got the plate I need for the cpu block, what speed did you manage to get your ram to run at also I was having super long post times because CSM was on after I switched to UEFI it posted much quicker so you might want to make sure its off too.
Edit: The setting for the UEFI is on the advanced\windows OS configuration you might not be having the same issue as me but my post was taken a life time it would just turn my display on and off until it finally showed post