Yeah close the side panel, doesnt matter if you have no fans on it. and the problem seems like its the room temp thats the issue here. 37c in a room is hella hot. you can only go so far with fans. i would try to lower the temp in your room somehow. and again 90c may not be comfortable but its still safe. gpus will even work in the 100c range, but then it starts to be a little bit dangerous