Push/Pull fans with radiator: Any benefit? What do I need to know?

Discussion in 'Cases & Cooling' started by CZroe, Aug 4, 2013.

  1. CZroe

    CZroe Lifer

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    I'm mounting a Corsair Hydro H100 (CoolIT 240mm closed-loop system with dual 120mm fans) in an old chassis that originally just had an 80mm top blowhole with the option to mount two 80mm fans in the top PSU bay (assuming you mounted the PSU in the bottom instead). I'm actually adding a 360mm grill so that there will also be a 120mm dedicated blowhole fan.

    What I REALLY want to do is go all-out with a push/pull configuration. What do I need to know?

    The two included 3-pin fans are probably higher SPI than typical 120mm fans, so I assume they would need to be left as the "push" fans. I bought more Corsair "quiet" PWM fans when I saw the 2-pack at Fry's. The pump/CPU water block supports PWM and this system will be loud enough as it is, so will these make good pull fans? I remember hearing many years ago when I made my first HTPC (AMD Mobile Barton in a Shuttle SN45G2) that Push-Pull only works when the pulling fan is higher CFM than the pushing fan, but that may only apply to that situation (80mm push air cooler with external 120mm ducted exhaust).

    I also have many 3-pin fans I can use including two Scythe S-Flex S-FDB fans. What's more appropriate? I don't have the Corsair Link thing for fan speed control though I may buy it. This case is going to be an absolute wind-tunnel so I think I can afford to run everything at the lowest speeds except for the H100 push/pull setup (plan to de-lid and O/C my Haswell i5 4670).

    Cliffs: What is there to know about Push/Pull configs especially as they relate to radiators? How should I use the fans I have available (2x PWM "quiet" fans, 2x Scythe S-Flex S-FDB quiet fans)?
     
  2. BrightCandle

    BrightCandle Diamond Member

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    The best fans for radiators are those with high static pressure. Gentle Typhoon's basically outperform everything at a particular amount of noise but there are a lot of options that are very close behind that. Recommended reading: http://www.xtremesystems.org/forums...0mm-Fan-Testing-on-an-MCR120-Radiator-Round-6

    As to push/pull configuration the radiator sandwiching is about the only guide I know on this, it does not go into the types of fans: http://www.xtremesystems.org/forums/showthread.php?220874-More-Radiator-Sandwich-testing. What I would suggest you do is make sure the push and pull on each side is the same fan, that way one won't be pushing/pulling the other past its capabilities and increasing the wear.
     
  3. tarmc

    tarmc Senior member

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    I didn't really see a difference going from single fan to push/pull with a h70
     
  4. Agent11

    Agent11 Diamond Member

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    Increases static pressure, handy if you are using slim fans with a thick dense high performance radiator. 38mm thick fans have more static pressure, and are considered the best radiator fans for dense radiators, if you have 38mm thick high speed fans like sunons or deltas in push pull you will have the best performance delta possible at your ambient temperature for that radiator...

    And it will sound like a jet engine, delta makes some pretty insane fans. If you are deaf or just don't mind 60+ db check these out.
     
    #4 Agent11, Aug 5, 2013
    Last edited: Aug 5, 2013
  5. tarmc

    tarmc Senior member

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    using a noctua nf-p12 I believe it is and works fine on its own
     
  6. Ayah

    Ayah Platinum Member

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    Actually, for a given airflow, a 38mm thick fan produces less static pressure than it's 25mm counterpart using equivalent geometry. A 38mm fan sacrifices some static pressure for less noise production.

    9G1212H1011 (38mm) produces ~42 Pa at 1m^3/min and 12V.
    9G1212A4011 (25mm) produces ~50 Pa at 1m^3/min and 12V.

    Both of these are Sanyo G geometries and run at 12V. The differences in RPM affect their static pressure. 2600rpm @ 38mm vs 3150rpm @ 25mm.

    If you want god of static pressure, Sanyo has a "new" amusing 48V fan. The 9HV1248P1G001 is a 120mm fan, 38mm thick, 11500rpm and specified for a maximum of 1300 Pa. (it also consumes 96W at full tilt...)
     
  7. tarmc

    tarmc Senior member

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    Wow prob loud as all hell too
     
  8. Agent11

    Agent11 Diamond Member

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    The catch is equivalent geometry. There are tripple bladed 38mm thick fans designed specifically for creating static pressure, such as the Delta EFB1212SHE.
     
    #8 Agent11, Aug 6, 2013
    Last edited: Aug 6, 2013
  9. BrightCandle

    BrightCandle Diamond Member

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    In terms of fan comparisons I don't know of any better reviews than the ones on xtremesystems. If you have some links to some ones showing 38mm fans outperforming on radiators I would love to read them.
     
  10. aigomorla

    aigomorla Cases&Cooling Mod<br>PC Gaming Mod<br>Elite Member
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    38mm fans always have greater static.

    having greater static allows the radiator to achieve higher efficency.

    HOWEVER... as u know of diminished returns.. the closer ur coolant is to ambient... it requires an a positive work value to bring the coolant below ambient....
    Meaning... as u get to ambient... the system becomes really inefficient... until u put work into the system... IE.. a compressor... to bring coolant below ambient.

    However.. 38mm fans will allow u to get away in some scenarios where 2 fans wouldnt. (tight spots)

    actually its the other way arround.
    38mm will sacrifice CFM for more static due to the aggressive blade geometry...

    the 38mm fan allows for a more aggressive blade angle to push air harder, however the vent out is more chaotic due to the higher static and not uniform like a penitrator for example.

    Regular Fan
    [​IMG]

    Penitrator
    [​IMG]

    You can see in an open enviorment... a regular fan would lose to a penitrator... however when its strapped in front of a radiator or an air sink... a regular fan with more chaotic dispersant is preferred.

    Penitrator type fans are GREAT in passive environments, where ur trying to get environment temp down...

    I dont think the 25mm san ace can EVER be as strong as the 38mm.
    Its just not possible due to the aggressive geometry.


    http://www.performance-pcs.com/catalog/index.php?main_page=product_info&products_id=27971
    70.4
    (0.283inchH2O)
     
    #10 aigomorla, Aug 6, 2013
    Last edited: Aug 6, 2013
  11. Killerxp100

    Killerxp100 Junior Member

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    2C difference with a D-14
     
  12. Ayah

    Ayah Platinum Member

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    I was only comparing equivalent geometry to compare 25mm vs 38mm since if you change any other specification, the comparison is invalidated.

    25mm: [​IMG]

    38mm: [​IMG]

    These are from Sanyo's own web catalog.
     
  13. Agent11

    Agent11 Diamond Member

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    In our applications these stats don't mean too much on paper.

    http://martinsliquidlab.org/2013/02...w-specs-are-poor-measures-of-fan-performance/

    'Just like pumps, it&#8217;s the pressure somewhere between these two points that matters in the real world and that isn&#8217;t static pressure and it isn&#8217;t max air flow, it can only be represented by a full P-Q curve.'

    As soon as a fan is strapped onto a radiator real life takes over.
     
    #13 Agent11, Aug 6, 2013
    Last edited: Aug 6, 2013
  14. CZroe

    CZroe Lifer

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    Thanks. You guys have given me a lot to read/think about. I doubt I will be getting a Corsair Link module to control the fan speed in software because it simply costs too much (more than the difference between this and the H100i which doesn't need it) and so I will probably just throw on two more identical fans even though they aren't PWM. Alternatively I may use four PWM-sharing fans, like the ones from Arctic Cooling. At least I can control them from the motherboard without that expensive Corsair Link and without opening the chassis to select one of the three speeds that the H100 offers (button on the water pump).

    Thanks again.
     
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