[SOLVED] How does RAM sync work?

[TLoke_]

I am buying another stick of DDR4 RAM. I can't remember if you needed to have the same sticks to sync them or something?

So I am asking I have one slot on my motherboard. Should I buy another 8GB 2133Mhz stick or a 16GB stick of RAM?

 

[CountMike]

I am buying another stick of DDR4 RAM. I can't remember if you needed to have the same sticks to sync them or something?

So I am asking I have one slot on my motherboard. Should I buy another 8GB 2133Mhz stick or a 16GB stick of RAM?

Ideally you should buy paired modules of 8GB, next up is another stick of same RAM you already have.