Intel,
please, please, please release a new driver that will not cripple the adapter (HD 4000)
the newest driver has no way of adding custom resolution, it's a big disappointment.
and seriously why would any manufacture limit the HDMI connector bandwidth, it makes no sense at all.
the only thing that can limit the bandwidth is either Intel driver or firmware. nothing else.
How hard can it be for the great "Intel" to release a fix that will enable 2560x1600@60Hz.
you will have to do it anyways, as the world is shifting to HDMI. now supporting 4k resolutions.
so why not start sooner than later. 
if Nvidia can do it, so can you.