I'm having the same problem.
I had a 1.6GHz CPU and replaced it with a 2.4GHz CPU and now it reads as 1.8GHz. I have 2048GBytes of RAM.
My P4VMM2 pcb 1.3 board, after BIOS upgrade, still reads my brand new 2.4GHz CPU as 1.8GHz.
My BIOS setup settings also say 'LOCKED'...
I didn't see any responses to your problems.
There are two CPU jumpers on the MB. They are labeled 1J1A1 (pins 1&2 shorted) and 1J1A2 (pins 2&3 shorted). That is the 100 MHz bus setting. I have tried to change them to the 133 MHz bus setting and the 'puter won't boot with them in that position.
The manual from the manufacturer says that the board supports CPUs of higher speeds and twice the memory that I have installed.
Does anyone know what the problem might be.