Maybe try mine, it's specialized in older hardware (CPU and GPU). I'm mining right now at 400+ h/s with my HD7850 2G
https://github.com/jceminer/cn_gpu_minerIt's almost getting annoying to read there's no decent CN miner for older hardware while my topic is on the exact same channel as this one and online for something like 6 months...
Just gave your miner a shot and seeing great results with 270 and 280 cards Thanks glad I seen this post