why my ddr4 ram is showing 1333mhz instead of 2666 mhz in cpu-z?

[roudy-s]

hello yesterday i have purchased 16 gb of ddr4 ram that is 8gb x 2 hyper-x furry at 2666mhz but when i have checked the cpu-z i see that is shows me 1333mhz only why is that and this is a picture showing what i mean
the picture

and another thing am i running in dual channel? any help will be appreciated and thank you

 

[SkyNetRising]

DDR stands for double data rate. There are 2 data transfers per clock.
Actual frequency 1333mhz means effective frequency 2666mhz.
CPU-Z is showing you actual frequency. You can calculate effective frequency yourself.

And yes - your ram runs in dual channel mode. You can see that in the screenshot too.