My wife had a similar problem with her XPS-15. Randomly during the night the laptop would warm up and cause the fans to spin up. Apparently this is caused by windows waking up. Initially I thought it was windows deciding to do an update, but even disabling that (if it is possible at all), the laptop would wakeup. Random trailing through the internet pointed to the useless Killer network drivers, or better the management application, to be the cause and uninstalling them was supposed to fix the issue. Anecdotally it seemed to have worked, but when I last checked the drivers seemed to be back.