You're going to need about 2 * 1200 watt gold PSUs for that beast imho. So that's at least $500 USD.
for 8 5770s? You're crazy. You don't need 2400 watts to power 8 5870s. A full system with CF 5770s was measured by anandtech as pulling 390W from the wall. Even ignoring the system overhead, 390W * 4 = 1560W. Many people have reported their AX1200s as being able to do that without too much fuss. Not a cheap PSU by any stretch of the imagination, but certainly not $500. More like $250.
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Anyway, would the big bang marshal be capable of supporting all 8 of these? The main reason I'm so attracted to making an 8-GPU system is because is because repurposing it is an easy way to drive a 12-16 monitor video wall without messing with (the highly buggy) xdmx.
Again, you run the potential risk of burning out the mobo if you don't provide power bypass for some PCIE slots. They will also need to be single slot 5770s or else you will need to use extenders anyway. If they are not single slot you will need some sort of custom built rig to hold all the cards in place as well. Some things to consider.
Also I still don't have confirmation one way or another, but some users report issues with getting windows to recognize 5+ physical video cards. If you planned on linux anyway not as much an issue.
Just because people say that a 1200 can handle 1560 watts.. doesn't mean it's a smart idea.
I like to get more than 6 months out of my $200 PSUs anyways... so I keep them all at 50% load.
A few things of note
1) 1560Watts is Wall power. PSUs are rated to deliver their labelled rating *to the system* (this is after AC/DC conversion). 1560watts (which is higher than the real amount used, I just used it for ease of demonstration) from the wall is ~1300Watts to the system, these are non-underclocked cards to boot, so the real deal will definitely use less power. But regardless, AX1200s are overdesigned to be able to produce that. Yes it is overloading, but if you really really worry about that, drop a $15 cx430 in the mix, solved.
2) lol @ 50% load. That's potentially the most cost inefficient thing I can imagine. Not only are quality PSUs designed to produce 100% of their labelled power (well read the label, 12v will be slightly lower than total), they are designed to do it continuously. That is 24/7/365. That's why a quality PSU comes with a 5 YEAR warranty. The manufacturer knows that they won't have to make good on very many of those warranty claiicms.
Why not underclock your CPU on your main computer to half clocks so it will last longer? Makes about as much sense to me.
I'm fairly sure power supplies are at peak efficiency operating at 50-75% load, but don't suffer major performance loss above that, only below. I know they are designed to operate at full load 24/7/365 though, the first thing to fail will probably be an electrolytic cap and they're cause for failure is rapid discharging or overvoltage.
