I had today this exact same issue with my K90, I tried to apply that K90 linux driver but still had no result, but then I found http://forum.corsair.com/v3/showthread.php?t=133929 ckb, in the usb.h i had to change 0x1b08 and 1b08 to 0x1b02 and 1b02 and everything worked perfectly, it’s kind of odd that in *buntu 16.04 it stops registering the XF86AudioRaiseVolume with corsair keyboards