I just bought a D54250wyk about a month ago, and have a similar issue.
My issue is that the fan speeds up at times and the cpu seems to keep an unusually high temp.
At first I thought that this had to do with something running in the background on the computer, but as I went into bios, I set the temp manually to 40%, and still, in bios, at 3300rpm, I have an idle cpu core temp of 62C.
I even waited in bios about 10min, and the temp went up to 62/63C.
How can this be on a lowpower unit like the nuc, in bios where there is no cpu pressure whatsoever?
And yes, I am using the latest drivers released on sep 19th.
I know 62 is below the limit, but this unit should have an idle of about 50-55C, and 62 on bios idle means that it's gonna have a hard time keeping the temp down at usage = higher fan speeds = more noice.