Everyone is talking about condensation but what you really have to worry about is bugs and other critters. You are creating a nice warm haven in an otherwise inhospitable environment

Bugs will be a problem. Ladybugs will seek out warm places to snooze through the winter. Every fall I get a few in my basement equipment.

Oooo that's an interesting idea. I'd love to hear if this works.

Edit: thinking further after I sent that message. Fans or fanless wouldn't change the amount of heat the computer creates. It's still going to create the same amount of heat. I'd leave the fans in, just putting it in the location should be enough.

https://www.reddit.com/r/homelab/comments/alcmhi/cleaning_snow_from_server_rack_in_helsinki_finland/

We have done a few installs in garages. Just ensure the system is protected from cold shocks. Everything in a sealed enclosure and vents with controlled fans that can adapt to incoming air temp.

I think condensation could present an issue at such low temperatures, but I've never gone quite that cold.