Having recently played with the idea of Bitcoin as I might have some servers just sitting around, I can tell you after a 30 day run of a few servers, I made the equivalent of roughly $5 in bitcoin from 3 servers. Two of the servers were E3-1240v5 CPUs, and one E3-1270v6. So doing some more research it appears the only way to make money mining Bitcoins is with the ASIC mining hardware.