Why is my r9 390 hash rate so low

I recently bought an r9 390 nitro and was able to oc it to 1200mhz (core) and 1600mhz(memory) however I'm only getting a hashrate of 22.3mh/s

I'm running windows 10-64bit with radeon 16.4.1 drivers

my bat file is configured as: ethminer -G -F http://us-east1.nanopool.org:8888/0xa09243dC6d89729d88189De91AFd808117196b96/neppu