I have X5660 / X5670 XEON CPUs in most of my rigs that also have GPUs.
These give 220-230 H/S on Monero or about 40 cents a day right now ($12.00 per month)
they cost me between $20-40 per CPU used so my ROI time is very fast.
You're blowing my mind right now. I hadn't thought that this route would be very profitable, but at those prices used you are talking some recent sense. That's some good ROI and the stations with GPUs could probably be converted into a sick LAN party is need-be. $12 per month, per CPU, is not bad at all. If you can be efficient with the space then that's quality mining. I personally prefer my GPU mining, but if you are working with limited funds or want to really build yourself up then this sounds spectacular.
I put them in my HP Z400 workstations (which I use as a base for my miners) which come with heat-sinks sufficient enough to run them at less than 60 degrees Celsius. Just pop out the crappy old CPUs that come in them, pop in the new XEON, apply new thermal paste, and bam!
I'm taking down all of this information, because I'm going to look into this and think about grabbing a CPU mining rig just for a test run. Is there anything to do with those old crappy CPUs?
Secondly I have 24 pcs Dell R815 running (I have 12 more I need to bring online)... 4x Opteron 6380 (16 core) per system giving 2100-2200 H/S total or about $4.08 per day right now ($122.40 per month) -- they cost me around $800 or so per unit used. I believe I can dial them in more but right now they use ~675 watts per system... quite profitable.
Would you consider selling any of the systems you haven't brought online yet? $4/day for one system is more than a single 1080TI is earning. That's pretty impressive. I'm baffled by this right now. You learn something new everyday, though. $800 is about what a 1080TI costs these days, too. Not a bad alternative, for sure. That sounds like heavy wattage, so I'm sure you can bring those numbers down.
ROI not as fast as the XEONS but I picked these up late last year when GPUs were completely unavailable. I figure... I can always hop on any new "CPU Only" coin and dominate it as well.
You sound smarter than most of these 16 year old Youtuber Bitcoin miners.