Rumours are that Nvidia plan to release their new GTX 880 flagship graphics card in September. Nvidia have scheduled a big press event in September, most likely to show off there new maxwell architecture probably aswell as a little push for their GSYNC and Shield products. The rumoured details of the card itself are it will have 4GB GDDR5 memory and 256-Bit bus. Pricing will probably be similar to launch price of the GTX 780 but we will see if Nvidia decide to offer this at a slightly cheaper price range. 

I suppose the big question is how much of performance advantage the GTX 880 will offer over the current gen GTX 780 and 780Ti?

GTX 880