# PC box air flow



## geosman (Sep 15, 2007)

With the recent heat my atx desktop is running too hot and so i have to shutdown. I just checked the fans (one at top back and one at mid height and about 3/4 back) are both exhaust.
Since the CPU and its fan are mounted near center opposite the side fan, would it be best to reverse the side fan to input? The side fan seems to have the greatest flow.
I have space for an additional fan at the rear and do have a bun fan I could install if I have power for it. Would installing it reverse of the other back fan create a better circular flow of air?


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## SpywareDr (Jun 15, 2013)

The goal would be to get the hot air out, not circulate it around inside the box.


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## Tyree (May 10, 2009)

You want front to rear airflow. Side mount fans commonly cause turbulence and disrupt the desired front to rear flow. Try disconnecting the side fan and see how it goes.
Fans are rarely the solution to overheating problems.
Is the CPU heatsink/fan free from dust buildup?
What temps are you seeing and using what to see them?
What is the ambient temp?

PC Specs?
Pre- Built Brand & Model Number
Custom Built- Brand & Model of Mobo-CPU-RAM-Graphics-PSU.


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## greenbrucelee (Apr 24, 2007)

As Tyree said, air comes in the front and goes out the back and/or top.


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## WereBo (Apr 5, 2008)

As above but, regarding side-panel fans it depends entirely on the individual PC (internal cable-layout, size of 3rd-party cards in what slot etc.). My PC has 1x80mm side-fan sucking out and that brings the temps down (HDDs and GPU) by approx 5C)

Other PCs are cooler with the fan blowing in, whereas others are cooler without a side-fan - It's purely trial-&-error for each PC.


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## geosman (Sep 15, 2007)

Ambient air temp: 27° C /80° F. Case temp is 37° C and climbing. CPU temp is 50.5° C which is above my alarm value after about 5-10 min from boot. When ambient is normally about 65° - 70° the CPU rarely gets above 46°C. Don't know which way the CPU fan runs, in/out but side vent is nearly directly opposed to it. PC temps coming from "sensors" command under Slackware and are correctly set up. No abnormal dust buildup. 
This has occurred before when the temp in the home gets high like this so I had set up "sensors" so that it would not hang the system when the temp is excessive like now.
Thinking if side fan is input cooler air would lower temp and exhaust to rear. Any other ideas?


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## Tyree (May 10, 2009)

Check the temps in the Bios. 
Try disconnecting the side fan.
CPU overheating is commonly caused by dust buildup, lack of sufficient clean power or dried thermal paste.
Knowing what were working enables us to assist you more effectively.



Tyree said:


> PC Specs?
> Pre- Built Brand & Model Number
> Custom Built- Brand & Model of Mobo-CPU-RAM-Graphics-PSU.


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## gcavan (Aug 13, 2009)

As stated by WereBo above, each PC is different and several factors will affect the layout and configuration of your cooling solution. The construction of the chassis plays a major part in how your cooling fans are configured; ie large areas of mesh often make intake fans redundant. 

However, a good starting point is usually a single, high efficiency exhaust fan at the upper rear (top or back, doesn't matter) and a second fan at the lower front configured as intake. A second exhaust in the rear and/or a second intake on the front may or may not make a difference.

Side fans may be configured as intake or exhaust or may be removed entirely. Some experimentation is usually required. I prefer to have a slow turning, high efficiency fan on the side forcing air directly at the CPU cooler and/or the graphics cooler.


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## Rataru101 (Aug 12, 2008)

I agree with Tyree on the side fan. In fact, I actaully swapped side panels on my case when I first got it. Meaning the panel with the fan grill was put behind my mobo on the right hand side and the left side (veiwing side) was solid with no holes anywhere. 

But then I cut out the the grill/fan hookup on the other panel and placed a 13 x 13 window in and swapped them back. So there arent any open holes on the veiwing side of my case or on mobo side.

But that is with 2 120mm front intake fans and 1, 120mm rear top, and 1, 80mm top back exhaust fans. All set on medium except the 80 which is on high.


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