All:
Reporting this as a clue to help track down the driver issues others are seeing that are making HTPC use nearly impossible. I'm building a new NUC 54250WYK with HD Graphics 5000 (replacing an older i3 NUC so my existing AVR/Projector should be deemed working fine).
I've observed three issues
1. In Windows Media Center trying to tune to a HD Homerun Prime channel. Any Speaker configuration other than 2.0 causes WMC to fail with a video error - and I get a curious 1 second audio loop for the few seconds it takes wmc to get the error. I've tried 7.1 and the 5.1s with the same result. WMC works rock solid at 2.0.
2. In Powerdvd 13 I am trying to use 'non-decoded high definition audio' to bitstream a high def audio disc. This results in complete instability in both the player (hangs) and also in the amplifier - my amp will stop accepting IR commands and I have monitored the amp 'hunting' for the signal format on a status page (denon 4311ci). The workaround is to not use this particular audio track - I'm really looking forward to a fix! If you need any additional info please send a message.
3. Channel Mapping in all configurations to my Denon is wrong (stereo, 3.1,5.1,7.1...) - several have no center channel output, lfe is routed to left rear and even stereo has left and right swapped. Workaround is to reboot and ensure the amp is on after windows comes up - seems to improve this.
This is a new build of 8.1 I just started yesterday so there's not a lot of junk from the past in it.
I've also tested my old NUC - it does not have any of these problems in the same situation.