Added a side fan, temps went up


Sep 27, 2010
Hello all,

I have a mid-range PC mainly used for gaming but also for occasional school projects/homework. The parts are housed inside an HAF 922 case, so airflow is not a problem. I recently put some filters on it, and switched the airflow from negative to positive (I'm a dust freak). I did this by reversing the top exhaust fan into an intake and then adding a large intake fan onto the side; the side fan is blowing directly onto the video card.

The only exhaust is the upper-rear fan, so this leaves me with three intake, one exhaust. My idle temps increased on the video card by 6C and the load temps went from high 60's to mid 70's. This worried me, so I switched the top fan back to an exhaust...this surprisingly had no effect on temps at all. Since the only net change here has been the addition of a large side fan blowing directly onto the card, I find it odd the temps increased instead of decreased...anyone have an idea as to why this happens?


Sep 12, 2011

It sounds like you had a well designed case. You may have done one of a few things.

1. Short circuited the airflow, air is now leaving before it gets a chance to fully circulate around the components.
2. The filters are to restrictive for the fans you have installed.
3. set the airflow in your case in such a direction hot air is drawn to the components on your motherboard and not away.

To test this you should set your case back to the way it was. And measure the temps, Re- establish your base line temps.

Add just the filters and see how much the temp goes up.

Add the side fan and test it as in exhaust and input fan. Test Each way.

Then test the negative airflow, this is my real guess where things are getting mucked up. Think of case like a hairdryer. Cool air goes in one side and hot out the other. If you reverse the flow of air things may get hot air on them that they didn't previously.

The better designed the case the less likely just adding random fans or reversing the airflow is to to good things.
The case is designed for maximum air flow. The top fan should blow air out of the case, a bottom fan should blow air into the case (heat rises) the front fan should blow air into the case, the side fans should blow air into the case and the back fan should blow air out of the case. If you change the direction of any of these fans then you will find that the temperature inside of the case will go up.