1| do you need to overclock now? no
2| should you OC in the future? Yes
3| Do you need to OC with the current monitors you have? NO
4| I'm not familar with that Aito PSU, can't get anything with a google search either. Please take the time to get a Quality PSU and then address the WC problem.
So here's how you should tackle the issues;
1| get a quality PSU
2| get a nice WC loop installed
3| OC the beast out of that machine.
Now you might say, Oh i aint splashing another dime on another PSU!
well then be prepared to shell out a good amount of money for replacing all the blown up parts in your case. A cheap manufacturer may be kind enough to replace the parts damaged by their hardware but in the case of a PSU, they expect that you know what its intended use is, that it wouldn't come near the 850W (or whatever wattage they advertise) and that you won't push the PSU to its limits.
But when they find out that you've not done the above, then all they'll say is this - "

have a nice day"
if you can get an NZXT Hale 80+ PSU, Cooler master or corsairs HX or TXv2 series or a lil costly but you can pick up a thermaltake 850W toughpower grand. I own one and its superb!
skimping on the PSU is like skimping on tires after buying a porche 911 turbo. You bought that car to take it to its limit, but itf the tires go out - you may not be on this earth to buy a new set to try out the cars abilities.

capiche?
about OC'ing ,my advice would be to start another thread and have more people look at the issue.
FYI - that 6950 is enough umph in that card to power either monitors for intense gaming sessions. I own a 6870 BE and i know i can push it with an OC on my Q9550 while gaming off a 46" LCD tv.
google search power supply calculator and fill in the places with your system specs. You'll then begin to see the full picture with system power req's. From the looks of that PSU, 82 USD for a 850W PSU that isn't even 80+ rated is kinda a deal breaker for me.(i used currency converter to see how much it costs in AUS)
these seem good candidates for your system (with Crossfiring in mind);
http://www.newegg.com/Product/Product.aspx?Item=N82E16817116012
http://www.newegg.com/Product/Product.aspx?Item=N82E16817116013
^ that answer
all your questions?