I have a Core i7 4770k with HD4600 graphics/audio (driver version 15.33.18.64.3496) running on Win8.1 64 bit.
I'm experiencing a strange audio dropout problem with the HD4600 audio. Basically the sound randomly drops out for around 2 seconds. As if being muted and unmuted (but with no visual indication on screen that any mute button has been pressed.
This happens when playing audio via any player on my PC (e.g. MediaPortal, iTunes, VLC, KMPlayer, YouTube, other web sources).
Sometimes it doesn't happen for hours, other times it happens as often as every 10 minutes.
This only happens when outputting audio via HDMI and HD4600. Audio works fine and never drops out when using other outputs, such as 3.5mm speaker jacks, which do not use the HD4600 audio drivers.
There is no CPU utilisation spike when the problem occurs, and no high memory utilisation. No jitter, skipping or freezing of video when it happens. No latency spikes shown in programs like latencymon either when the dropouts happen. Video keeps playing as normal, the sound just mutes temporarily. No sync problems either - when the audio comes back it is perfectly in sync with the video.
I've tried switching and reinstalling all codecs and filters one by one and the problem happens regardless of which codec/filter is used.
I've even tried switching HDMI cables and using a different input on my TV, also without success.
I'm out of ideas so any help / solution suggestions would be massively appreciated!