I start to mining by XFX R9 280x 3GB DDR5 and hashrate is 15Mh/s but hashrate should be 20 or up
cpu intel core2due e6550 2.33GHz
running this code
ethminer --farm-recheck 400 -F http://127.0.0.1:8080/rig1
-G --cl-local-work 256 --cl-global-work 16384
Please advise you how to solve my problem and increase hashrate?