Popatim: Yup... Backside, just like the H7 which (from my experience with the H7) can be a little awkward when the so-called "X-bar" doesn't line up perfectly. When it doesn't line up perfectly, it can be very difficult getting all four holes to do so on motherboards with large VRM heatsinks.
H7 installation instructions here:
http://www.cryorig.com/inst_guide_dl.php?id=9
Neither is anything like Cryorig's original R1 or its H5 mounting design, each of which are screwed through the top to arms/bars that are securely affixed to the backplate.
Mounting instructions for the C7 were not available on Cryorig's website.
I would have preferred the fan use standard mounting holes in case it ever died and required replacement or if someone wanted to use a more powerful fan for greater airflow. With registration, Cryorig offers up to a 6-year warranty on its products, so consumers may not ever need to use a standard fan as a replacement.