# Computer Fan: Suck or Blow

**URL:** <https://boards.straightdope.com/t/computer-fan-suck-or-blow/229502>\
**Category:** Factual Questions\
**Created:** [February 16, 2004, 4:48pm UTC](https://boards.straightdope.com/t/computer-fan-suck-or-blow/229502 "2004-02-16T16:48:11Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Flash-57](https://avatars.discourse-cdn.com/v4/letter/f/839c29/32.png) [@Flash-57](https://boards.straightdope.com/u/Flash-57)\
**Post date:** [February 16, 2004, 4:48pm UTC](https://boards.straightdope.com/t/computer-fan-suck-or-blow/229502/1 "2004-02-16T16:48:11Z")

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I’ve installed a couple of new components inside my computer and it now seems to be running a little warmer than I’d like – no big surprise. So, I went down to the store and bought an extra fan to mount in the computer to cool it down. But, it looks like it can be mounted in one of two ways, either to blow relatively cool air from the outside into the computer or to suck warm air out of the computer.

Which way results in more efficient cooling of the guts of my computer?

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**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\
**Post date:** [February 16, 2004, 4:51pm UTC](https://boards.straightdope.com/t/computer-fan-suck-or-blow/229502/2 "2004-02-16T16:51:14Z")

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Front - suck, rear - blow. The front one should be near the bottom, probably with a gap below the front panel to allow air in, and the rear one should be high up, above the PCI/AGP slots and near the processor. If you’ve only one fan, have it at the rear.

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**Author:** ![Kinthalis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kinthalis/32/16084_2.png) [@Kinthalis](https://boards.straightdope.com/u/Kinthalis)\
**Post date:** [February 16, 2004, 5:19pm UTC](https://boards.straightdope.com/t/computer-fan-suck-or-blow/229502/3 "2004-02-16T17:19:37Z")

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Also, try to aim for a slightly positive airflow pressure inside your case so as to help prevent dust build up.

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**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\
**Post date:** [February 16, 2004, 8:00pm UTC](https://boards.straightdope.com/t/computer-fan-suck-or-blow/229502/4 "2004-02-16T20:00:21Z")

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Yep, you should have some at the bottom which suck air in, preferably through a filter, and some at the top which blow air out. You should have more suck power than blow power to allow for leaks through things like the peripheral bays.