Well, I think those numbers are at the wall, also. The Guru3D figure doesn't say exactly... here:http://forums.atomicmpc.com.au/index.php?showtopic=264
Ouch, 862W for just the cards. That's 72 amps right there... If there are overclocks involved here then I think you need 100 amps minimum (margin, efficiency, aging)
Turbo-cool 1200W is good for 90A 12V.
I really don't know about your booster. Have a look at the reviews at jonnyguru... there was a review last year on one, and he may have covered it there. Probably connects to the main PSU and there are probably instructions.