bignastyid :
860w is plenty for a 5930k and a 980ti or 2. The 1000w p2 will run 2 980tis and have abundant room for overclocking.
Just to piggy-back on this: Would you consider a 850w unit enough to comfortably run the OP's system (or the one in my signature) with dual 980Ti's, which have been overclocked to the max on their third party air coolers?
Are we getting too close to max capacity and is it safer/advisable to go for a more powerful unit, considering the higher energy consumption and cost of the PSU??