Electricity Question

[tenshou]

I just purchased 10 rigs with 3 7970 cards each.

With these rigs running in 1 room in my house, what modifications do I need to make in order to be safe? Last time I ran 4 rigs from a single socket and the circuit breaker kicked in, turning off the electricity.

Do I need to have an electrician come in and install a 50 AMP breaker and outlets?

Thanks

[mitty]

Let's say each 7970 takes 200w
Add in 100w for CPU/motherboard/etc + PSU inefficiencies, for a total of 700w per rig.
700w/rig * 10 rigs = 7000 watts total

Circuits continuously loaded need to be de-rated to 80% of their original rated load, so...

A standard 120-volt 15-amp circuit can safely carry 1440 watts at continuous load. (actually 1440 VA, but this is a conservative estimate so I think the difference between watts and VA when using decent PSUs shouldn't be an issue)

A standard 120-volt 20-amp circuit can safely carry 1920 watts.

So you would need four 120v 20a circuits, or five 120v 15a circuits to run your rigs.  (and that doesn't account for air conditioning)

Most rooms aren't wired for this amount of load so you probably need to install some new circuits.  If you're lucky the room will have 2 dedicated 20-amp circuits only used for outlets in the room.  In that case you could simply switch those circuits to 240 volts and you'd be all set.  You most likely need to have an electrician (or yourself) wire up a couple new circuits though.

Your first step is to figure out which circuits provide power for the receptacles in the room, what those circuits are rated for (should be the number printed on the circuit breaker(s)), and what else is powered from those circuits.

If in doubt it's best to call an electrician or a friend who's comfortable doing this type of work before you create a fire hazard. 

Good luck!

[lsvpa]

You would also need a way to exhaust all that hot air and pull cooler air into the room.