I actually experienced the exact same issue with my Windows 8 install on an ASRock CoreHT 252B Mini PC, which acts as my HTPC. Probably the same or similar as you, I'm outputting both video and audio ...

This driver supports Intel Iris graphics, Intel Iris Pro graphics, and Intel HD graphics for 4th Generation Intel Core Processors with Intel HD Graphics 4200, 440, 4600, 5000, 5100, 5200 and 5300.

This driver supports Intel Iris graphics, Intel Iris Pro graphics, and Intel HD graphics with 5th Generation Intel Core processors, Intel Core M with Intel HD graphics 5300 and 4th Generation Intel ...