Hey, please help.. I have radeon 580 8gb.. i start to mine with 21,5 mh/s, after 3days 21mh/s, after 2-3 days 20,800 mh/s, now 20,260 mh/s ? Why i lose Mh/s? Sorry for my bad English.
Driver Alone can't reached the 29-30mhs hashrate, you need to mod your GPU's in order to achieve this, a lot of guides out there, example below posted by Mattthev. you have to at least checked what type of memory you had and proper timings.