You should check/monitor the "
Core X effective clock" in hwinfo instead, as only it will tell you the real clockspeed your cpu was running at in said benchmark..
I only monitor core 0 and 1 as these are my best cores, together with my average effective core clock. (screenshot below not from any "bench session")
View attachment 22002
Highest single threaded i've managed in Cinebench R20 is 546 points, and a .multithreaded score of 10300 points
CPU-Z = 579.9 singlethread and 11786.5 multithread
All numbers above with PBO enabled