If you add another GPU to your system the MOST is can add is 138w, NOT 200. Also, that 250w value is so incorrect. There is no physical way your CPU uses 250w. It is physically impossible. Wattage readings are never accurate unless you measure with a kill-a-watt device.
Also, no you are incorrect. A 700w PSU delivers 700w at 80% efficient. Did you even click my link. It shows your PSU providing 787w and still being 80+BRONZE efficient.
I promise an accurate measure of your system will show, with 2 7950s will never go over 600w. You are 10000% in the clear.