all ddr4 is based on 2133.
what you bought is a set of ram modules that are rated/tested for 2666mhz.
Important things you need to know:
Does your motherboard support the 2666mhz?
1. If so simply go into ram or advanced ram settings and select XMP profile 1 which should be the settings for 2666mhz.
2. If not, what speed does it support. Find more info about the motherboard and/or memory modules and try those settings
For example my mobo is 2400 2800 3200. I was able to get 2800 but when i tried for 3000 it doesnt load up even though the settings are in and the pc boots properly, it shows overclocked at 2800mhz.
I tinkered a bit more with voltages and latency and got it to run at 3200mhz =)
fyi, as long as you only adjust things you...