The max wattage I saw when running my 5 5870s at 950/150 1.150v was 980 watts, so that won't leave much wiggle room. Personally, i run off a Seasonic 1250W PSU, which I know are rated for 100% continuous capacity. I do not know how Cooler Masters stack up, but I hear they are pretty good, still don't think i would run one at 100% full time though.
you can speculate if it will work or not all you want but I can tell you from EXPERIENCE
I am currently running 4 rigs with 5 x 5870 and 1000watt PSUs and have been doing so for almost a YEAR
believe me it works, if that coolermaster is 80plus it will have no problem just make sure you have an least one powered extender