Upgrading RAM (Adding RAM to current system)

hello everyone

 

i hoping get some info before i upgrading my RAM

my current ram is Corsair Dorminator 6GB (CMP-C7 series)

when i thinking to get another 3module set, my shop said they dont have it onstock... they only got Corsair Dorminator GT atm

 

now i wonder the compability

i know to work best i need same set

but will i get issue if i am adding with different set

i mean if i using my current dorminator (3module) then i am adding dorminator GT(another 3 module), will it be a stability issue ?

 

also i want to know, how to work with XMP?

as it will be different XMP and the bios seems only permit one XMP setting at a time

 

thank you in advance for helping me

There is absolutely no way to guarantee compatibility even if they were the same part number.