At a steady 60c here, I would be worried about lifetime of the card just to get 20% more bitcoin. It will take about a year for you to pay off a new card with that 20% extra. Probably just me.
Makes sense. Bit of a long term strategy though, I don't think OCing voids Sapphire's warranty and even then when you RMA it you'd have to mention it for them to know. I doubt this'll be a viable mining card after the 2 years runs out, so I'll probably end up selling it before then. Resale + earnings should be enough to buy an AISC. Just my thinking.
Would you mind sharing your clock speeds and settings?
I found running the diablo kernel increased my output by about 10%.
Interesting I just tried Diablo kernel earlier tonight and didn't notice anything. What settings are you using?