HD 4000 No longer powering high resolution monitor

After updating to windows 8.1 and installing the new intel driver for HD 4000, I can no longer run a custom mode of 2560x1440 at 55hz over hdmi.

This worked fine for months, but now I get the bandwith exceeded error in custommodeapp.exe

Please help, but please don't tell me HDMI 1.4 does not supply enough bandwidth, because I know it does. Not only does it say so in the literature, but I was doing it flawlessly for a long time, until the new drives came out.

Is there another version of custommodeapp.exe that I can use, that won't limit me?

Thanks