I remember watching there financial report and it was wrote that the 800 series is planned to Q4 2014 but because of somes problem at there manufacturor, they delayed it to 2015. An article said that they will maybe one high end model (like 780-780ti) that will be set at Q4 2014 but that's not sure.
Here the link about the article: http://www.kdramastars.com/articles/21159/20140505/gtx-800-series-news.htm
Here the link about the article: http://www.kdramastars.com/articles/21159/20140505/gtx-800-series-news.htm