I am wondering what would be profitable miners or multi-rigs if overclocking is the initial intention.
"October" KNC Jupiters can be over clocked from 550 GHs to 650-675 GHs fairly easily, and will draw about 825 watts. I've seen them for under $4000 on eBay.
One could buy a pile of antminers for that and not overclock them and beat that easily. $2400 for 720 GH before overclocking. The power consumption would be higher but you can pay for a lot of power with $1600