do you work for nvidia?
jk, i think it would be around 2 months after the 790 to try to get ahead of amd. it is rumored that amd will be releasing a 295 in around 3-4 months which is supposed to be 2 fully enabled 290 cores on 1 pcb. sounds impossible but only time will tell. a early release of the 800 series would draw attention away from this. this would get the cards in circulation and by the time amd has their new series refined to release to trump nvidia, nvidia can release ti versions of the mid and highend cards to combat this (860 ti, 880 ti). also a good sign is that devils canyon revamp of the haswell series cpu will be out and people that have been waiting to upgrade will go with this or broadwell. if they release the initial 800 series around the same time as the revamp and then the ti's around the time broadwell is released then it ensures optimal sales figures. but like i said its just my guess