Has anyone else's hashrate essentially halved using RX480?  I was never getting world-class hashrates (~23MH/s) but now it's down around 13MH/s for the two RX 480s that I'm testing. [ETH/ETC mining]  For reference,  I'm dual-mining SiaCoin and that halved as well from 7xx to 3xx.

Disclaimer:  I did install an RX 570 into the system to test,  didn't get the results that I was after so disconnected the card and uninstalled the AMD drivers completely before reinstalling 16.9.2. 

Suggestions?