Readback '0' about ryzen-5800x3d-linux-undervolting HOT 1 OPEN

Are you using Ryzen5800x3d ? If the register are not right the program will work but the readback indicates that these were not the right register where to write to - on most other CPUs this is the case. Alternatively BIOS may be preventing writing to these registers by overwriting them. Important bit is that these writes are so low level that if the driver manages to write them then the only way to see if they are OK is to read them back. Any other process or BIOS capable of writing to them can overwrite them immediately at will. Its sort of similar to embedded programming.

from ryzen-5800x3d-linux-undervolting.