Anything worth doing is worth doing right, right???
Our current setup is 8 rigs, each with 8 GPUs (primarily GTX 1070), in one standard US datacenter rack:
Each rig has a G3930 CPU, an M.2 adapter, 4GB of memory, and 2x1kw PSUs.
Rather than try and jam all that gear into a 4U case, and deal with cooling nonsense, everything is shelf-mounted. We are still able to service if needed, but this is far cheaper, and easier to cool.
Only change we have really made in the last year was due to using the NIST5 algo (thanks https://bulwarkcrypto.com/ ). NIST5 increased power utilization (heat), and needed to add additional cooling (this part is not as elegant, but it works)
OS: Ubuntu
ETH: ethminer + eth-proxy
ETH: Averages a bit over 2,000Mhs on nanopool.
Shameless Plugs (with my referral codes):
Cryptopia - Forget mining, buy coins!
Binance - Its popular, because it works.