Son benchmarks on a 580 4G on epoch 500, that is more than 1 is still 7 mh/s ...
That means the Zombie Mode will be for a long while... At the moment is the most profitable solution connected in MOBO for a 4Gb Cards with 24-25Mhs
the only problem with zombie mode is that you need a gen 3 PCIE and cannot use risers...
It will be nice if it works on gen 2 pci-e