From a previous business, I have 5 Dell Poweredge 2850 Servers, each with 2 Intel Xeon 3.4 Ghz processors. I also have 2 2950's, a huge 7150, and few other smaller 1 U Dell servers. All but 2 of those machines are just sitting there in the rack and not even turned on right now. I have seen CPU miners and know that these are not optimal, but have considering making 5 mining servers out of the 2850's to just see what happens. My power bill increases around $400 a month when running all of these servers/switches/UPS/Firewall/etc. (more in the summer than winter of course). I have all the infrastructure and hardware to setup these machines, but I can't seem to find any data on potential earnings with Xeon processors to see if it would be worth my time or the extra power to build miners out of these machines. I understand that with the difficulty going up the earning will continue to decrease, but if anyone could provide some rough potential numbers or suggestions for further research, it would be appreciated.