N150 machines come with or without fans, the chip is cool enough to run passively with a decent heatsink.
e.g. https://www.minix.com.hk/products/minix-z150-0db-fanless-min...
The ones with fans tend to be cheaper and have better sustained performance though.
ASUS PN42 is also passive, but they do not mention it. You can find this out from teardown pictures. They also have certified 32GB memory sticks from Crucial.
Looks like the whole tiny case is the heatsink, I like it.