Turbo boost not working

[GoodGuyNick]

When I try to use sudo undervolt --read I get:

sudo undervolt --read
  temperature target: -8 (92C)
Traceback (most recent call last):
  File "/usr/local/bin/undervolt", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/dist-packages/undervolt.py", line 445, in main
    voltage = read_offset(plane, msr)
  File "/usr/local/lib/python3.10/dist-packages/undervolt.py", line 204, in read_offset
    write_msr(value_to_write, msr.addr_voltage_offsets)
  File "/usr/local/lib/python3.10/dist-packages/undervolt.py", line 79, in write_msr
    os.write(f, pack('Q', val))
PermissionError: [Errno 1] Operation not permitted

Then I disable Secure Boot.
undervolt starts working. I configure it to run automatically on boot (systemd) and after that Turbo Boost stops working properly.
To fix Turbo Boost, I need to set undervolting to 0.

After more testing, I've found out that undervolting lower than -70mV results in a constant 3.6 MHz, the closer undervolt to 0 the more processor will boost. On WIndows I was able to achieve stable -125mV.