I've got a big problem with this. Best solutions I've found so far

1) If your machine is in front of any vents, move it so you can get decent airflow throughout the room.

2)I set up my computer right next to my window so the fans will blow outside. That helps some as well.

3) If you can't have your pc in front of your window, try putting a fan up to blow out the window. It helps get all the hot air out and the cooler air in from the vents.

Unfortunately, there's no way to cool down the pc itself other than underclocking it and using it less.