As said in your
other thread, 300w is still 300w(or whatever the actual value the PC uses while you game), regardless of how hot or cool the components themselves are operating at.
It's still mixing with your room ambient and heating that up. The more power you use, the faster that warms up, as well as increases(until it reaches an equilibrium).
It needs to be immediately directed out of your room or solved by force, or nothing will change.
Moving the PC to another room and running it from there, as suggested by Eximo.
Brute force it with air conditioning.
Install a fan in the window to suck the air inside your room, which is being warmed by the PC, and blow it outside. Might be slow-going, or ineffective, depending on the relative distance of the PC to the window.
Install a pedestal fan next to the PC, aim it at the doorway to your room, and remove the heat that way. Might be closer than the above method.