Zdenekk :
I just cant overclock more than 1600Mhz at memory clock i had 1700Mhz in sapphire trixx for a little while now... My graphics card is MSI R7 260X 2GD5 OCV1
did you download and install the full installer package or the basic web based installer? also, if you installed using the full package did you install the update for it as well? did you make sure that you grabbed the right version for your OS?