850w is good for two 1080 ti and one 1070 at 80% which is 520w (based on the 250w TDP from standard 1080ti and 150w from standard 1070)
850w for 24/7 usage is 680w so you have room of 130w for CPU, storage and ram.
That's what I think but somehow it don't
So to stop offtopic I'll share some of my mining strategies with 1080ti:
1. Straight Coin mining:
1080ti is a beast in certain algos and petty player in others (
Ethash)
Best bets so far with 1080ti based on overall performance are (in my subjective order): Skein, Blake2s, Lyra2v2, Skunk, Nist5, Tribus, Bitcore, Equihash.
You choose one coin from the algorithm and mine it. Pretty simple, You can also use profitswitch miners to mine Your coin on yiimp pools.
Then You are selling aroung 80% of your coins at 1-5 days interval based on market (It's important to choose coin that You believe in so You won't panic at dumps).
The coins I'd recommend are : DGB, Verge, Bitcore, Solaris, Zen/Hush (It's my personal list so don't take it as best option).
That way (by mining straight DGB on blockfactory) I managed to get 13% of my overall investment in month.
20% of coins mined builds pretty solid base for future price rise.
This method flaw is that sometimes (on dumps) You can't cashout immediately.2. Profit-Switching Mining with to-BTC conversion:
Taking list of algos from previous method We can set up profit switching software to mine "most profitable" (based on network diff/pool hashrate) option and convert any coin mined straight into BTC.
That works on pools like Zpool and Hashrefinery (You can also use it with right conf file to mine on official Yiimp pool but without conversion).
This method let You cashout in fact less often than method 1 (especially if You are mining on Zpool), because Your coins need to be traded to BTC on exchange so process can take up to 24h untill Your earnings are credited.
It could fluctuate a lot depending on current market situation and You dont have any control over coins You mined.
BUT it is almost set and forget build so for someone it could make a job.
Depending on number of Your 1080ti's You could see payments from 4h to once a week ^^
3. How can You squeeze more:
Personally I'd recommend some POS coins to run (but need of remote control over rig implicates some vulnerability for running wallet at same machine), like 808, Bitbean, Orbit, Solaris(yea).
Next if You have free disk space (more than 10 gb) set it for Storj share, it'll bring you few bucks a month, but will add up. For larger disk space (like 1TB+) set some of it for Storj and rest for Burst mining. When Your Storj get full lower Burst file and so on.