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CPU cooler but no case fans

Discussion in 'Overclocking & Cooling' started by VirginStranger, Jan 26, 2019.

  1. VirginStranger

    Associate

    Joined: Aug 11, 2013

    Posts: 19

    I have a 3rd PC haven't used for a while , recently been testing it out, it's a 5 year old i5 4670, Be Quiet Dark Rock cpu cooler, 8gb RAM, Corsair CX550 PSU, no graphic card anymore i sold it on. Long story short the 2 x 120mm case fans where very noisy running at 100% as connected to PSU, they're 3 pin so with my limited knowledge didn't want mess about trying to sort out how get them connected to 4 pin slots on motherboard. As i said this is my number 3 backup system and no gaming, nothing intensive at all will be done on it. I will passing it onto someone else as a nice gift to them and they will only run as browsing/music/movies about 5 or 6 hours at day and they like a quiet machine, so with me disconnecting the case fans it now runs nice and quiet and temps average around 29 to 33 centigrade according to all temp monitors i've used. I know its heresy and i'll probably be hunted down and lynched for saying this, but surely there is no need for case fans based on what the system will be used for and that at least its got a pretty decent cpu cooler with reasonable temps ?
     
  2. Grandmaster Fap!

    Sgarrista

    Joined: Jan 10, 2004

    Posts: 9,092

    Location: T'Northwest

    No you are right, depending on use its possible to not have fans at all BUT, i myself would have at least a very low speed fan exhausting what heat is produced just for peace of mind that the cpu isnt cooking.

    If its all just getting up to 33 while playing movies and browsing then i think you are good to go :)
     
  3. doyll

    Soldato

    Joined: Jul 1, 2011

    Posts: 7,239

    What's been said.

    i5 4670 is only 84 watt TDP, but even 84 what with no airflow gets hot.

    I would plug one of your 3-pin case fans into 4-pin header and see what fan does. Many 4-pin fan headers are actually variable voltage, not PWM. If they are PWM fans will run at full speed same as plugged into PSU. Look at motherboard manual and find the fan header. It will tell you what they are. All you need is a fan behind CPU cooler pulling air out of case. Then set the fan curves to low rpm up to something like 80c at full speed for rare emergency when they need to be moving more air.

    Problem with no case fan is if someone did start to do a high load application (like encoding a video) the system would overheat very quickly and while usually system will shut down when too hot, sometimes they don't and that could result is serious damage.
     
  4. billysielu

    Capodecina

    Joined: Aug 9, 2009

    Posts: 10,798

    Location: Oxfordshire

    1 in 1 out minimum
     
  5. doyll

    Soldato

    Joined: Jul 1, 2011

    Posts: 7,239

    1in 1 out is an okay rule of thumb, n reality it's stacking fans, same as push/pull on radiator or air cooler. Sometimes it helps because stacking fans double their static pressure rating (if airflow is straightened between fans) and this increase in static pressure mean the can overcome the resistance of filter/grill better. Sometimes additional fans help move air to or from component better too. So 1 intake in front and 1 exhaust behind CPU cooler might develop a good airflow path. Honestly, I haven't built a system with an exhaust fan in a couple of years now, and I built several a month. All I use is good pressure rated intake fans and end up with nice cool and quiet performance.
     
  6. CageyH

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    Joined: Nov 28, 2011

    Posts: 58

    This is interesting to me, as I am contemplating building a fanless PC for music and streaming movies.
    I am using an old PC - Core Duo Q9550 (I think) on an Asus P5K motherboard. I know this is now obsolete, but it still works.
    I have a Zalman FX70 CPU cooler, and an Asus GT1030 graphics card, running of an EVGA Supernova 550w G2 PSU, all housed in a define R5.

    I currently have the two fractal GP14 fans running on minimum setting using the case fan switch as intake, and two Noctua 120mm fans (I don’tbremember the model, but likely to be a redux version). One is an intake in the bottom of the case, and one as an exhaust behind the CPU cooler.

    I recently changed the graphics card from a Zotac GT710 to the passively cooled GT1030 and my temperatures dropped.
    The PC does everything I need, and stays within a good temperature range. As such, to get it even quieter, I am thinking of losing the case fans and using air convection to keep it cool. If I have no fans, I can open the moduvents on top to let the hot air out. If I did this, I will fit a dust filter on top.

    Is this a crazy idea?

    What is the worse that could happen?
    If the CPU or motherboard die, it is a good excuse to get something more up to date.
    As long as my HDDs, PSU and graphics card survive I would be happy.

    My intention is to start reducing the number of fans in the case, one by one, until I get to a sensible compromise if required, but theoretically could I be 100% fanless with the top of the R5 completely open?
     
  7. LuckyBenski

    Wise Guy

    Joined: Dec 28, 2017

    Posts: 2,263

    Location: London

    I'd say that's a pretty hot running CPU but I guess if you're happy at present, it can likely be tweaked somewhat. I think there's a big difference between minimal case airflow and no case airflow. I've had cases that just heat up continuously in the roof, and a single 80mm on minimum will clear that hot air from collecting.
     
  8. CageyH

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    Joined: Nov 28, 2011

    Posts: 58

    I agree it’s normally pretty hot, which is why I don’t want to go fanless straight away.

    With the four fans spinning slowly, the CPU Max temperature was 39 degrees C after a couple of hours last night.

    It has a mild overclock as well, which Indon’t really need. I plan to turn that off, and then start disconnecting fans one at a time.

    If I open all three of the vents in the top of the case, no heat will collect either. The PC will also be silent apart from the mechanical HDD noise.
     
  9. doyll

    Soldato

    Joined: Jul 1, 2011

    Posts: 7,239

    Not crazy at all. Define R5 has a good size bottom vent and top vent for bottom to top airflow. You might not be able to do it with no fans, probably a bottom intake at low speed is all you will need. I've found raising case up with some 20-30mm spacer blocks under the feet greatly improves airflow to bottom vent. Removing bottom vent grill also improves airflow and lowers noise levels, but probably don't need to go that extreme. Bottom intake at low speed will be inaudible, especially if case is setting on carpeted floor.

    Might help to turn CPU cooler so it's width is front to back instead of bottom to top. This will allow more airflow in. At least that's what I've found when doing similar builds.
     
  10. CageyH

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    Posts: 58

    Thanks for the tips on the CPU cooler.
     
  11. CageyH

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    Posts: 58

    Having just checked, I am not sure I can turn the Zalman FX70 around. It may clash with the me,or etc.

    Anyway, I disconnected all the fans, and the max temperature on one of the cores was 49 degrees C. This was after two hours of a typical load on the processor. This seems to be well within the limits of the 71.4 degree C max allowed on the CPU.

    With fans blowing through the case it never really gets above 39 degrees. I could fit a single fan on the FX70 and I am sure it will be even lower.

    However, as the idea was a fanless PC, I think that can be achieved even on hot days here in the South of France.
     
  12. doyll

    Soldato

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    Sounds good to me. Maybe leave a fan or 2 installed so in case you ever need it you can just plug them back to increase airflow.
     
  13. CageyH

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    Joined: Nov 28, 2011

    Posts: 58

    I have left all three in place, connected to a Phanteks fan hub. All I need to do is plug the feed onto the CPU header, and away I go....
     
  14. mattyfez

    Sgarrista

    Joined: Apr 12, 2007

    Posts: 8,941

    Also if not bothered about overclocking, then set the CPU back to standard speed and see if you can under volt it.
    If you can reduce the voltage then there's less heat being generated in the first place, so less need for cooling.
     
  15. CageyH

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    Joined: Nov 28, 2011

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    So undervolting is like a reverse overclocked?
    Keep lowering the voltage until it becomes unstable and pop it back up again?
     
  16. Grandmaster Fap!

    Sgarrista

    Joined: Jan 10, 2004

    Posts: 9,092

    Location: T'Northwest

    Exactly, some chips can operate on really low volts so undervolting can really reduce the heat and still get the same performance if you are lucky :)
     
    Last edited: Feb 4, 2019
  17. doyll

    Soldato

    Joined: Jul 1, 2011

    Posts: 7,239

    If temps are a little high with no fan try one case intake at low speed or CPU cooler fan at low speed. Often one or the other will move enough air to keep things cool with no noise.
     
  18. CageyH

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    Joined: Nov 28, 2011

    Posts: 58

    CPU set to the lowest voltage possible. Speedstep also disabled.
    Time will tell if any of this makes a difference.

    Next step is to replace those noisy spinning data storage devices. With a silent PC, you can hear them, even though they are isolated.
     
  19. mattyfez

    Sgarrista

    Joined: Apr 12, 2007

    Posts: 8,941

    The noiseyest parts in my PC at idle are the three spin drives I have. And thats in a lian li case with rubber grommets on all the HDD mounting screws.. They just vibrate even when idle.

    For a media rig then going solid state for storage would be a big thing.
     
  20. CageyH

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    That is the plan.
    I have ordered a 500Gb SDD for the system drive.
    I will order another 1Tb for the media library.