I have a 850 watt psu, a motherboard that can only support 2 way sli/crossfire, and 2 1080p monitors with a HDMI and DVI connectors. Budget is around 600-1000 dollars depending on money from Christmas and sales. Power consumption is not an issue as long as it will work on my current psu(I don't pay the energy bill). Looking to get 40+ fps on most games. What would be the the best graphics card solution for 4k gaming at near maxed settings?