To my knowledge, if the fan is not variable speed or controlled by hardware, your not going to get what you want. The fan doesn't show up , most likely no controller for this. Those baby's ran hot anyhow, I always keep canned air around to keep all heat sinks free from dust and debris.
I have an old dell Lattitude XPi running win 3.1(look that one up haha), and she runs hot as hell. I also have an old Acer Extensa 711TE that will roast out as well.