I have problem with start srbminer 1.6.8 on rig with 4 r7 260x 1gb... I have not change any parameters... Just start AS IS... Does srbminer 1.6.8 supports old cards like 7790 or r7 260x?
AMD Radeon R7 260X is Bonaire so it should work.
What error do you get, paste it here, or create a screenshot.