A:AnswerYes, absolutely that is fine and is exactly how my build is setup. It is very common to only utilize 2 of the 4 ram slots and then add an additional 2 sticks later
A:AnswerHi,
Yes, this memory kit is compatible with that combo. After installation, please enable XMP in BIOS to utilize the rated 4000 MHz speed. Feel free to let us know if you have any additional questions: support.corsair.com
-Albert