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Thread: Suck or blow

  1. #1
    Join Date: Mar 2013

    Location: nottingham

    Posts: 328
    I'm nigel.

    Default Suck or blow

    I recently bought cheap a Onkyo AV Receiver, one of the models with overheating problems...a TX-NR 905.
    A brick shithouse thankfully all functional...the graphic chip on the HDMI board is still working.

    I have attempted to alleviate some of the excessive heat issues by heatsinking the I.C.s on the graphics board but think some active cooling will be needed.
    So...if I go with mounting a fan, do I force cool air in....or suck hot air out.?

  2. #2
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 5,540
    I'm Alan.


    Blow air in.
    Turbulent air will 'stick' to the radiating surfaces better than laminar air and absorb more heat. Hence it is better to blow air over as the air is turbulent coming out of the fan (due to the blades chopping up the air).

  3. #3
    Join Date: Apr 2011

    Location: cheltenham

    Posts: 665
    I'm matt.


    Not sure how you're planning to do it but i've just recently built a new pc, so my knowledge is reasonably fresh on the subject.
    Bigger fans are better because they can be run slower and make less noise than a smaller fan that is spinning faster to move the same amount of air. If you are using a pc fan, you can get filters to help keep dust out of your machine (they come in standard sizes). I use Arctic F14 and F12 fans in my pc because they come with a 10 year warranty and are good value for money.

    Most agree that you are better off having more fans blowing in than sucking out because this helps keep dust out (assuming you have filters on the input fans). If it's a sealed unit i'd think about either having one big fan pushing air in and one smaller fan sucking air out or at least adding some vents to let the hot air escape.


    If you want to direct air straight over the problem area, the Arctic P14 will focus the air into a smaller area. These are more like what you'd get on a GPU or CPU, rather than the F14 that is just a case fan.

  4. #4
    Join Date: Mar 2013

    Location: nottingham

    Posts: 328
    I'm nigel.


    Thanks for the replies...I've dug around and found a couple of 12v fans, or from a old PC psu and one from God knows.
    To keep noise down both are currently running on 6v wallwarts..
    I have them just sitting on the lid....no room inside for a permanent mount...I have a friend who fabricated metal (called him a welder once and he nearly punched me)...I'll see if he can mount them in the lid without destroying it..

  5. #5
    Join Date: Apr 2011

    Location: cheltenham

    Posts: 665
    I'm matt.


    Make sure you use filters or you will fill your amp with dust in no time.

  6. #6
    Join Date: Jul 2014

    Location: Shropshire

    Posts: 2,376
    I'm Anto.


    Could you use 2 , one to input and another to suck it out? The thread title make me think of other things
    I only ride 'em, I don't know what makes 'em work

  7. #7
    Join Date: Dec 2014

    Location: Surrey, UK

    Posts: 392
    I'm Phil.

    Default Nice big dumplings?

    What on earth is going on?

  8. #8
    Join Date: Mar 2017

    Location: Seaford UK

    Posts: 1,528
    I'm Dennis.


    My instinct is to suck out because the vacuum will then pull the air into the cabinet from all the source openings, and this will be very turbulent and reduce laminar flow. Blowing at the hot item will cause a bounce, rather than engulfment.

  9. #9
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 71,851
    I'm Grant.


    Grant .... ؠ

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    **Iíve studied deeply in the philosophies and religions, but cheerfulness kept breaking through**
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  10. #10
    Join Date: Mar 2017

    Location: London N2

    Posts: 1,782
    I'm Edward.


    I opened this thread only as I have a filthy mind.

    But as I'm here I'd suggest two fans - one blowing in and the other sucking out. As oddball suggests.

    Typical PC way of doing things.

    If you find the fans you have make too much noise try Noiseblocker fans - virtually silent at 1m. Or slow down your existing fans with resistors.
    Main: Tidal/Roon > MiniITX > Metrum Hex > Phast > either Radford STA25 V or Trilogy 968 > Tannoy Berkely.
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