You Probably Only Need Two Or Three Fans In Your Computer

When you build a computer, your case probably comes with a couple fans, with room to expand. But do you need to? The folks at Linus Tech Tips decided to find out.

There are a lot of different variables here, but they tried to test as average a configuration as possible to see how much different fan configurations affected temperatures. They found that, once you add a couple fans to the case, any additional fans do improve temperatures, but only marginally.

There are a lot of diminishing returns, that — depending on your preferences — may not be worth the added noise those fans can cause.

Of course, this changes significantly if you're overclocking, or live in a particularly hot place, but it's interesting to see some actual numbers behind a typical scenario. Check out the video above for the full test and results.

Case Fans — How Many Should You Have? [Linus Tech Tips (YouTube)]


Comments

    With a typical tower standing normally, aren't most graphics cards installed in such a way the fans are facing down?

    This seems counter-productive to wanting the air to flow through the rear of the case like the other components do?

      Graphics card fans are intakes and (depending on card and design) blow the air either directly out of the case or dump inside the case for chassis fans to move from there.

      Depends on the case, really. Not all are designed the same.

      I thought it was weird too until i realized it sucked in from the bottom and blew out the sides, not blew hot air downwards

    I have a Deepcool Steam Castle case, the motherboard sits horizontally which means the heatsink and fans are upright with the 20cm front fan drawing air in, and the rear exhaust fan. It stays rather cool, it is currently sitting at - 43 degrees for my 6700K CPU OCed to 4700Mhz/core, a 7970 GPU - 54 degress. I did have it OCed to 4900MHz/core but dropped it back a bit. I wonder if the top fans really are doing anything overly beneficial

      Only thing those top fans do is stop warm air from collecting at the top of the case.... while at the same time providing a great way for dust to get in and settle.
      They are kind of necessary... but realistically, a few open vents and the back fans should be enough.

      top fans should be sucking in bottom and blowing out top .... heat rises

    Basically you want airflow THROUGH the case. Doesn't really matter which way although cold from the bottom and hot out the top is ideal.
    Be aware though that fans on the bottom can and will pull in more dust too.
    I find usually front to back is good but make sure you have enough clearance at the back (eg not closed in some desk draw).

    As for internal components.... those fans don't do as much if the hot air isn't being forced out of the case. Their job is to get cool air over the heat sinks and push it away... doesn't matter which direction, but they do need to be sucking in cool air and not the same hot air that they just blew out.... see first point.

    If you have water cooling or radiators then again you'd have to consider air flow through them too... no point forcing warm air through a radiator either.

    As stated above, simple way to understand it...

    Front and Bottom: AIR INTAKE
    Back and Top: AIR EXHAUST

    Fun-fact: 99% of cooling fans blow their air out of the side that has the sticker on it.

    My PC has...
    2x 120mm fans running intake at the front (1 is stock, 1 is a silent aftermarket)
    1x 120mm exhaust fan at the top-rear (stock)
    2x 140mm Cougar HDB fans as exhaust on the top
    All fans are connected to a 6-dial fan controller, which can throttle between 40-100%

    The 140mm fans were the most expensive, $25 each. They're actually designed to be intake fans, because Corsair says they create a vortex of air, which as a result, produces a higher yield of force. However, my GPU is an MSI R9 390X, which has two of it's own fans on the card. For these GPU fans to perform optimally, I need to ensure my case has a negative pressure inside (on-board exhaust fans work better in negative pressure environments). If I placed the Cougar Vortex fans on the bottom of my case, they'd be pushing more air in than my single 120mm rear-exhaust fan could get out; as a result, I'd be creating a positive pressure environment in my case. The GPU fans would start working harder because of that and their air-exhaust would be almost nullafied entirely.

    The Cougar Vortex fans still do really well as exhaust fans. On a normal day I can get my ATI card running at 50° under load, which is insane. On a hot day, when I dial them up to 100%, my ATI card can go from a hot 80° down to low-60's.

    Anyway, moral of the story: Don't blow your PC, use fans.

    im @ 35 degrees CPU 8 core i7 with twin fan 110 corsair RAD on top (idle 60deg full load)

    2 120mm fans intake front turned off that i can turn on when it gets 40 deg days
    and 1 120mm rear fan exhaust

    bottom intake is PSU and the PSU fans dont even spin up (great design corsair, love it)

    blower titan X that blows all its heat out the back

    never see temps over 60-70 full load so no hot air blown in case whatsoever

    funny thing about my case is when it heats up it Creaks.... metal warming up hehehe

    Last edited 30/11/15 5:23 pm

    I got one front intake, 2 top exhausts and a rear exhaust. MSI 970 and a coolermaster 212 hyper on my CPU blowing air towards the top exhausts (Also helping move some of the GPU air I suppose. Did some tests before and after setting it up that way and didn't notice much difference temp wise if I'm honest lol).

    PSU is corsair, fan never turns (I went overkill just for that). In theory you only need one intake and one exhaust to 'suggest' the air to keep moving away from the warmest parts.

    PC is relatively quiet in silent fan mode, but always very cool. B)

    Edit: Also. Love Linus Tech Tips. If you're a tinkerer or like PC news you should really keep up with them.

    Last edited 30/11/15 6:14 pm

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