How come nobody actually reads???
Don't dual mine SIA if you are running out of power or your miners are overheating, mine it directly without ETH and you will make slightly more until the next difficulty retarget.
7970/280x mines at 900MHS/s $3 per day per GPU ! You won't make that much with ETH currently.
I never even tried dual mining, only direct SIA and it still does 10c+ more on the cards compared to ETH only, really profitable on the mentioned cards tho.