Ram mis match

[dominikcalvesbert99]

So currently I have 2 4gb sticks of ddr4 2133mhz ram and 1 stick of 8gb ddr4 2133mhz ram.
I need to know whether I can use all three sticks or would it be harmful to do so

 

[Calvin7]

On memory that has never been tested together, you can do your own testing.

Since you don't mention what you intend to use it on, I wouldn't know about the other part.