When i got my D54250WYK it had bios 024 on it. I was using minidp to hdmi adapter at the time. I got the nuc logo with boot options with bios 024. After updating to bios 025 the nuc logo and boot options are gone, it just a black screen until it boots into windows 8.
Just got a new mini hdmi cable and now the nuc logo and boot options are back.
My bios settings for output is set to "auto".
Is this a bug in the latest bios?
I am sorry you are having problems with the NUC system but let me help you.
At this point I have not heard about this problem with latest BIOS for this unit but based on your description I would say that the latest BIOS is incompatible with mini DP to HDMI adapter.