Please post your system specs. A few people seem to be having issues with Windows 8.1 at the moment. Windows 10 is a free upgrade til the end of the month if you wanted to use that OS instead.
I am having the same issue and just figured I'd tag off of this thread. The card isn't being detected by the radeon control suite when I download the win8.1 drivers.
MOBO Asus Z87-A
Ram 16g DDR3
and obviously a rx480 8g
Edit: Just upgraded to Win10 to deal with the issue instead. Didn't really want to but whatcha gonna do.