Let's say you spent the low-end of $200 for your 7850 cards.  Those *alone* would cost you $120,000.00.  Never mind the motherboards, CPU, RAM, ELECTRICITY, etc.  You may mine upwards of $580.00 daily ... but that's still a pretty long payoff.

What I want to know is, where did you get the startup capital to do this?  Where do you buy 600 MSI cards?  I am assuming that took you a while.  I would think that even high volume retailers don't keep that quantity of a particular card on-hand.  And as others are wanting to know - what does your electric bill look like?  I hear stories of "free electricity", but trust me that doesn't last.  Even if your rental contract doesn't have an abuse clause, any judge in his right mind would sign the eviction order to throw you out.  And if you live in the States, you can expect a visit from the DEA.  :-)