I just install Blockchain drivers and all is become fine! 27-28 Mh/s from one card.  

I use this timings:
777000000000000022C39C00AC595A3D90550F12B84C8408004006007E0514206A8900A00200312 0100F292F94273116 // 1216/2000

Unfortunately i dont know what timings were in stock. I bought cards not in shop. They were already overcklocked. I tried modifie bios and got much bad results. Around 20-23 Mh/s/

Yes, this happens after the DAG file is generated. And it can be and vice versa, first 24-25 Mh / s and when generating a new DAG file, again, 28 MH / s. Gpu not hungs. Clocks are the same. Different only power consumation. On 24 Mh/s it is less.

Hi! Can you help me? After few time mining i have problem, that mining reconnect and my hash falling from 28 to 24-25 Mh/s. Se my screens. And i add bios.



https://drive.google.com/file/d/0B4amPrusv5nfY0xWV3FDemxpOUE/view?usp=sharing