Hi, I just rebuilt this machine a couple weeks ago, and the machine runs very hot. There is a place to mount a case fan in the front, but not in the back. I had an idea of mounting a case fan on the power supply in the case. If I position the fan to blow into the power supply, won't that help my heat problem with the computer since the hot air can escape though that. I would rather do this than buy a new case since I am on a budget.

I doubt your method is effective and efficient. If you have access to some drilling tools or cutting tools, maybe you can mod your case to put an exhaust fan on it. Remember to put the exhaust fan in a higher position near the back because hot air is light.

Why don't you first make sure the power supply fan is running at something like full speed and that it isn't clogged with dust. Usually a power supply is adequate to exhaust hot air from the case. Good housekeeping inside the case is also important. Insure ribbon and other cables don't block the airflow from the front lower intake area to the power supply. A properly mounted cpu heatsink/fan and attention to the details of good airflow thru the case should be adequate to cool your machine. If your motherboard can report temps, let us know where it's running. Skip