I'm thinking to buy new RAM (for Lenovo 320 15AST, motherboard is LNVNB161216). I had 4GB, I need 8GB. My current RAM is m471a5143sb1 2133Mhz, CAS (CL) 17, PC19200.

I was looking at two with such specs:

Crucial [CT8G4SFD8213] 2133 Mhz, PC17000, 15-15-15-36

VS

Patriot Signature [PSD48G240081S] 2400 Mhz, PC19200, 17.

First is a bit cheaper, has frequency that no more that baseboard provides, lower latency, but lower PC (also I'm not sure which PC my baseboard provides).

Command su -c 'dmidecode -t 17' shows that Speed is 2133 MT/s But specs on internet for my RAM (m471a5143sb1) tell that it has 2400Mhz. Does it mean that my motherboard locks down RAM's frequency ?

lscpu gave me this:

CPU family:          21
Model:               112
Model name:          AMD A6-9220 RADEON R4, 5 COMPUTE CORES 2C+3G
Stepping:            0
CPU MHz:             1491.819
CPU max MHz:         2500.0000
CPU min MHz:         1300.0000

I was looking if there settings that locks down RAM, it seems there no, but I not sure, so I'll put these photos here: