Must the fan be 25mm high? Or can I use fan with heights of 15mm or 38mm, for example?
Is the fan mounting kit supplied with the main board a “must”? Or are there other viable options?
if there are other options, will there be a note in the guide that shows how to mount a fan that doesn’t answer to the fan mounting kit screws height (which, again, I assume is designed to support fans with 25mm height)?
The max height of the fan will depend on your case, so we cannot tell. With the case provided I guess it’s max 25mm. For the screw I would hope the fan come with it’s screw that fit the fan.
15mm will fit, but it won’t work properly with the duct. In general, it’s going to be quieter and much better performance using a 25mm. Unfortunately a 38mm won’t fit in the case.
The fan mounting kit is a must to get the right length fasteners and to be able to use the duct.
Just some quick feedback here but tbh I think most people who are interested in using the mainboard in a separate case will want to avoid using the fan duct since it significantly reduces height clearance and only really functions well if it is hugging the side of the case. Even then, from my experience with SFF PCs fan ducts / shrouds have a modest impact on temps at best (like 2 degrees C maybe?), and I would think that additional case fans exhausting the hot air would have a similar, if not greater benefit.
Given this, is it really not possible to mount any fans at all without the duct attached? I would think that you just need to use shorter screws than those provided for the duct kit, perhaps the screws that come with the fan would work? If not, it would be helpful to have lengths that work for 15/25 mm fans without the duct. Even though the smaller fans would definitely be worse, it opens room for using this in sub 4L cases, and some users might prefer going as small as possible, even if that means having to use power and performance limits to cool the chip properly.
An important piece of information I might have missed: I plan to use my own SFF PC case, hence the question regarding the fan with 38mm height.
My concern was that the screws which are supplied with the fan mounting kit (by Framework), would not work here. I will, of course, aim to use a fan with 25mm height for best fit - but, more options are always better.
I currently have a Noctua 15mm fan fitted and it works fine. I needed to use M5 10mm Nylon spacers with the supplied screws, but it works totally fine. There are zero issues with cooling performance. The system barely turns on the fan.