Setting minimal cpu fequencies

[Bernard KORSEC <bernard.korsec@xxxxxxxxx>]

Dear Sir,

I have installed Ubuntu 18.04.1 LTS on my ACER Aspire ES1-523, and I 
would like to setup the frequency of the 4 processors of my AMD64 to 
1000 MHz, permanently.

Please, could you provide the instructions to do so ?

Thank you.
Best regards.
Bernard.