Can you mix kingston memort

Hi newcomer and welcome to the Tom's hardware forum.

Yeah, after few minutes looking for that both RAM, I found that have the same CL and voltage, that is me most important when you want mix RAM. So, you can mixed without problems.
 
Usually not, but in some mobos, the problem is the chipset that don't support a determinate size of RAM, for example 4GB, in that case, you can install the 4GB but the chipset only recognize 3GB or 3.5GB.

For example, my current mobo. I can install 8GB, but the mobo only can recognize 7GB for the chipset limitation.