Siddharth18 :
Dear Community, Straight to point I have an 8 gb 1866 mhz adata ddr3 ram which i have plugged in also i have a kingston 1333 mhz 4 gb ram, so should I install both of them in my mobo or should i only run 1866 mhz ram with 8 gb mem. or should i get 1333 mhz on both ram sticks and get 12 gb of memory please help.
Technically speaking you should buy a 16GB kit(2x8).
Mixing and matching RAM modules isn't recommended. That's when the specs. are identical. Mixing and matching specs. is not supposed to be done in any circumstance.
I would just install the 1866MHz RAM modules. Your next step, if you need more RAM should be an identical module or a new RAM kit(preferred).