corsair vengeance 2800mhz?

[J3ST3R]

Hi all, looking for the advice of a computer genius! Lol

 

I bought 2x 8gig corsair vengeance 2800mhz ram as an upgrade my pc for dcs. I installed the ram but after looking in the bios, noticed that it is only recognised the ram at 1333mhz? How can I change this to 2800mhz so I'm getting the most from my ram?

 

My motherboard is a asus z97 pro.

 

Ps, I don't know if it makes a difference but the ram is seated in the 2 and 4 (grey, not black) slots on the motherboard as the sticks won't fit into the 1 slot because of the heat sink on my processor.