http://superuser.com/questions/119755/hdmi-with-resolution-2560-x-1440-possibleIt's an older thread but I thought I would add my two cents in. Running Windows 8.1 RTM on a Retina Macbook Pro which has a NVIDIA GeForce GT 650M connected to a Dell U2711 via HDMI I managed to get it working by creating a custom resolution using the following settings (note the CVT Reduced Blank selection):