My NUC8i7BEH is supposed to have a fan but I’ve not heard it or felt any air movement from it.
I do recall the case being slightly warm once after it had been running 3 grouped zones all day. I’ve had doubts about the fan being enabled after reading some posts on the noise. But have not had reason to check.
It’s in a media closet with fresh air drawn in from the bottom front and exhausted in the rear at ceiling height.
Please read my second reply in this thread again.
Ah thanks, didn’t see that.
Better be safe than sorry, since I haven’t been doing hardware diy before 
I suspect it’s the same motherboard between the two but not certain by any means on that. i.e the SATA connection is present in both. If so a future upgrade if required could be a new third party case with room for a SDD/HDD
Same motherboard but it is either M.2 or SATA SSD. Not both due to bios.
NUC computers have a small size fan. In idle mode you will not hear any noise. It will start making noise under heavy load like playing video or video conversion. For the most part you will not hear much during audio conversion etc. I have NUC5 computer that running 24/7 and over the years its fan started showing signs of wear and tear. It’s whirling noise is more audible right now. Unfortunately replacing this fan is nearly impossible. I was not able to locate proper replacement part. Is it possible to passively cool NUC computer? Yes, but you will need industrial type casing and remove existing fan. This website LogicSupply.com has this type of computers.
I imagine 8i7BEH is M.2 SSD, with the option of adding a 2,5" HDD
Yes. Don’t buy the NUC8I7BEK. That one doesn’t have the option of adding a 2,5 inch SSD.
I thought it is merely a chassis (physical) limitation? I checked the Intel download for the BIOS, they seem to share the same BIOS file, but I’m not 100% sure.
If changing to a fanless chassis, that may no longer apply.
According to the Intel technical specification sheet the BEK version doesn’t have a second SATA connector If I recall correctly. So it’s not only the chassis
I think it was a gen5 model that someone said he couldn’t get both to work.
Please have a look at these annotations. If a H is present in the modelname, a 2,5" HardDrive is possible to connect. If a K is present, there’s no HardDrive slot.
And since Roon themselves recommend 8i7BEH, that model must has pretty good performance 
whats the problem with a simple 6i5SYH? Does an 8i7BEH sound better? In my opinion an i7 Nuc is overkill and does not do anything with audio at all, or am I wrong?
Then either order from a company offering fanless NUC builds at additional cost (there are several), or get a used unit with a fanless chassis.
But I upscale to DSD128, therefore at least i5 has been recommended in this thread
Just before you haven’t done it before, doesn’t mean you can’t do it
I’d imagine it being a fun little project to do
Where would you buy one? I’d thoroughly recommend the 5th gen i5 I have for smaller collections. It can upsample to 512 with room to spare and runs very cool in an Akasa Plato case. But they are rare (and expensive) new and are not popping up on the second hand market with any regularity. We have to point people in the direction of hardware they can buy.
