20 rigs with 4 7970's and power questions.

[fruitcommander]

I'm building a huge rack scrypt rig for a customer and when it's all said and done, it will demand about 25,000 watts. They are flying me in to help them select a space to store this monster and I have some serious concerns about power.

When I'm looking for space to lease, what kind of modifications should I be thinking about having to make, or what should I be looking for in terms of powering this thing?

[Alphi]

i used to work in a datacentre.. what kind of location are they planning to deploy in?

ideally you would want a location that has its own circuits and backup power supply.. a lot of offices that exist within the same building share circuits so if you start tripping circuits your going to get some seriously angry neighbors.

you'll probably need 10 or so 15AMP power lines if you live in a 240 volt country... if you live in a 120volt country like the US im not sure what lines they use for high powered I think it might be 30AMP.

don't forget to add 20% or so power if you plan on overclocking the GPUs... and then you need to space them out and provide power for additional cooling...

I have a couple of 7970s and they can easily pull 20% more than the rated power when pushing them upto and past 700khs

you'll also want to make sure you run your gear across as many power circuits as you can for redundancy so that if you trip a circuit breaker it doesn't shut down the entire operation.

just as an example.. the average house where I live maxes out at about 8,000W-10,000W  small offices are probably less because they share circuits...
so if you wanted to run that kind of operation from a house or small office then you would need to get extra lines put in from the power company. which can be costly...

[fruitcommander]

This will be in a garage, so I'll call an electrician to see how much a line would cost.

[Alphi]

This will be in a garage, so I'll call an electrician to see how much a line would cost.

tell him how much power you will need and he will be able to tell you how many lines etc they can do.. he will probably shit himself but I cant see why the power company wouldn't oblige since your going to be paying them a lot of money for the power....

the only other thing is that some police agencies and other authorities watch for houses which consume vast amounts of power because its usually a sign that something untoward is happening (ie like a marijuana growing operation or drug lab etc) so expect them to come snooping if you draw that kind of power 24/7

[fruitcommander]

Thanks for the advice, my GPU supplier nearly fainted when I made an order for 80 cards this morning.

[kalus]

i used to work in a datacentre.. what kind of location are they planning to deploy in?

ideally you would want a location that has its own circuits and backup power supply.. a lot of offices that exist within the same building share circuits so if you start tripping circuits your going to get some seriously angry neighbors.

you'll probably need 10 or so 15AMP power lines if you live in a 240 volt country... if you live in a 120volt country like the US im not sure what lines they use for high powered I think it might be 30AMP.

how feasible would it be to run DC current through a farm like this; e.g. one big honking power supply to rectify the 3-phase AC for the whole garage.  

[mattopia]

25,000 watts at 120 volts is over 200 amps.  Unless you locate in a commercial space that is equipped for that sort of power, you will need the utility service upgraded.  If you are talking about locating in "a garage", that suggests residential for me.  Most homes in the US are on 100 or 200 amp service for the *whole house*.

That's a lot of heat to move too...  The power and cooling restraints will be more of a challenge than building and racking the rigs I suspect.

If you locate in a data center, usually 60+ amps of service per rack is no big deal, and they already have the environmentals taken care of.  You would just need to design around a standard rack-mount case, or build your own frames that fit in a standard 42" rack. 

[Alphi]

how feasible would it be to run DC current through a farm like this; e.g. one big honking power supply to rectify the 3-phase AC for the whole garage.  

firstly I'm not an electrical engineer I was a hardware engineer deploying rack mounted solutions so ALL of the power and cooling requirements we needed were taken care of with a few phone calls to the Data centre maintenance people.

the thing is.. with a 25Kw constant power draw you would be talking about a VERY large bank of batteries something that could probably power 4-5 average size residential houses...

the problem with a mining rig is the power draw doesn't really dip and spike because the load is pretty much as close to 100% as you can get.. ie its pretty much constant 24/7 if you set it up right..
so in that sense DC battery banks (or UPSs) are only going to help by cleaning the power and protecting your gear from short outages and lightning strikes etc.

so if I read your question right using a DC system would only provide maximum protection for you gear and away for other forms of energy to be supplied to your mining farm (eg if you were going to add wind turbines and solar panels etc)

Additionally that kind of power would be extremely dangerous for anyone to play with that wasn't a fully qualified electrician with years of experience.. its difficult enough trying to set up a DC backup system for a residential house with solar panels and wind turbines let alone trying a system that could power 4-5 houses..

I think that's the beauty of SCRYPT mining... it really does force the mining to be decentralized more so than SH265 mining because the cheapest and most effective way to deploy a system of that size would be to split it up over 2-3 houses/locations.

[EvertonFan]

an 80 gpu rack in a garage? I sincerely hope they have thought about security!