Your power supply is sufficient, but is fair. Two hard drives, two graphics cards (powerful like that) in parallel running at once, and that much RAM If you do not change now, the have to change later (soon) if that is what you plan to do. The setting is fantastic, but the power supply is just as you say and could create bottlenecks. A power 1000W should be enough.
Something like this:
http://www.hardocp.com/article/2012/11/13/seasonic_x1250_1250w_power_supply_review/#.UdwH5D4W5-U
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341046 <-- SLI ready
http://ocz.com/consumer/psu/fatality-1000w-power-supply <-- SLI ready
http://www.corsair.com/professional-series-hx1000-80-plus-certified-modular-power-supply.html
Anyway, it depends on the budget you have.
In conclusion, as you now have your PC settings, not all the performance and sucrase surely create bottlenecks and the source will "forced". If you can, buy one of at least 1000W. It is also an investment for the future.