Edit: I currently have two gtx1050 in it running at full power, and can't hear the fans at all.
Edit: I currently have two gtx1050 in it running at full power, and can't hear the fans at all.
Fans don't tell the whole story. Network traffic is super useful to see as well. Also, if your computer never gets hot enough, it can be doing plenty of unwanted background work without setting off the fans.
I often run the engine to heat my water and the very slightest change of tone has my ears pricking up, panicking with "I've not heard that sound before! What's up with it? Is it broken? Am I going to sink??" running through my head.
There are also power button remotes that could work, depending on distance: https://www.amazon.com/dp/B01MQUANS8/
I screwed four lengths of 4" x 2" between two roofing joists to make two trapeziums. I then screwed a 3/4" thick sheet of chipboard to the bottom and then wrapped the top and sides in roofing felt (some protection in case of roof failure).
The loft is lagged 200mm deep with 3/4" chipboard on top which deadens the noise nicely. The Dell was running the fans quite a lot today when I went up to check on something - 25C outside in Somerset, UK today.