How fast is too fast? Fan speeds?

Discussion in 'iMac' started by MythicFrost, Oct 24, 2010.

  1. MythicFrost macrumors 68040

    MythicFrost

    Joined:
    Mar 11, 2009
    Location:
    Australia
    #1
    Hi,

    I've bumped up my fan speeds using smcFanControl, I've currently got the optical drive and hard drive fans spinning at 3k rpm and the CPU fan spinning at practically max which is 2k rpm -- GPU, CPU, optical drive temps, etc., are all dropping, but not the hard drive -- can I boost the hard drive fans safely to 5 or 6k rpm? and the optical drive fans too? or will they break lol?
     
  2. Spike88 macrumors 6502a

    Joined:
    Jan 25, 2010
    #2
    For me, I set my iMac's minimum speed to 1,600 RPMs. With iStat, I often see them spinning at 1,800 RPM. I find anything over 1,800 RPM, I can start to hear its fans. At 2,200 RPMs, I can definately hear them. At 3,000 -> 5,000 RPM speed, I bet the fans start sounding like my HP Laptop fans. re: Ready to spin their bearings out. Like any moving part, too much not always a good thing. Hopefully, you don't over spin the fans too long and shorter their life expectancy.

    As a suggestion, use iStat program and do many RPM vs. internal temp samplings at 200 RPM intervals. Try to determine where additional fan speed creates no dramatic cooling benefits. Sometimes, faster spinning fans create heat themselves. Thus, faster spinning fans is counter productive. For my iMac, setting its fans to 1,600 RPM (which means they spin at 1,800 RPM) is most optiminal (from a "best cooling") perspective.

    Good luck - based on your iMac usage.

    .
     
  3. xlii macrumors 68000

    xlii

    Joined:
    Sep 19, 2006
    Location:
    Millis, Massachusetts
    #3
    What is the typical temperature in the room where your iMac sits.
    Just using the iMacs default fan speed what are the iMacs temps when not under load.
    What are the iMacs temps when you are playing a game, running handbrake, ... putting your machine under a load.

    If you post the temps... others can tell you if your machine is running normal... running hot or running cool compared to their machines.
     
  4. George Knighton macrumors 6502a

    George Knighton

    Joined:
    Oct 13, 2010
    #4
    Is there a proved, quantifiable reason for not allowing the system to monitor and control its own fan speeds?

    That sounded sarcastic. I didn't mean it that way. I am just curious what it is that I might be missing. :)
     
  5. ECUpirate44 macrumors 603

    ECUpirate44

    Joined:
    Mar 22, 2010
    Location:
    NC
    #5
    I agree. Why bother adjusting the fan speed manually when Apple puts all those sensors in there to do that for you.
     
  6. Spike88 macrumors 6502a

    Joined:
    Jan 25, 2010
    #6
    Hi MythicFrost.

    For my iMac, its modified FAN RPM to internal Heat Relationship details are:

    http://i178.photobucket.com/albums/... iMac system/FanControlSettings2010-08-30.png

    http://i178.photobucket.com/albums/w251/Spike99-Pictures/New iMac system/InternalTemps2010-08-30.png


    For me, having "slightly" tweaked fan speeds inside an iMac is a good thing. It allows me to keep my iMacs "proactively" cooler. I find many factory defaults are set for "re-active" cooling configuration. And when things get too hot before "extra cooling" kicks in, it takes more effort to bring the high heat back under normal range. Thus, I like proactive cooling configurations much better. Just like I installed an extra aux transmission cooling ATF rad in my "normal driving" vehicle as well. To me, slightly "better then factory" improvement for proactive cooling approach is a good thing. But.... Some folks feel the "too late" dummy light or "too late" auto shut down configuration in their iMac is better. Each to their own.... To me, the "too late" reactive default configuration isn't the best approach because at extreme high temps, the heat over-load damage is already done. Just like an over cooked vehicle transmission, when the system shuts down (or dummy light comes on), it's too late.

    As mentioned in my above post, use 3rd party fan control software and "tweak" in 200 RPM intervals. And, compare to internal heat reduction gains. If 1800 RPM gives best cooling (for your usage needs), then leave it at 1600 - 1800 RPM. Works for me (and my iMac)...

    Good luck in your "cooling tweaking" as well...


    .
     
  7. MythicFrost thread starter macrumors 68040

    MythicFrost

    Joined:
    Mar 11, 2009
    Location:
    Australia
    #7
    Thanks, I'll fiddle with some different speeds :)
    I'd say the temperature is currently around ~28-30c -- my biggest problem is my hard drive which is 60c.

    The hard drive really just sits ay 60c no matter what, it is 30c when I start the computer up though; in CS:S (on Mac) I've gotten the GPU (diode, iStat Nano) up to about 83c otherwise it sits around ~64c, under load the CPU sits ~60c IIRC otherwise ~45c, ambient is 23c, memory controller / optical drive ~ 52c, GPU heat sink is usually a few degrees lower than the GPU (it is now, anyway).

    Blasting the fans at 4k RPM and the CPU fans at 2.1k RPM will produce a CPU temp ~38, GPU temp ~50c, hard drive temp ~50c, etc., much lower, and I'm sure it'd continue to drop.
    Because it's hotter than I want it, I think the hard drive is being throttled although I'm not sure.
    Thanks for your help man :)

    I'm not sure whether I'll leave them at stock or keep them tweaked (I'll see what benefit I get); what is the "'too late' dummy light configuration"? I'm not a dummy but I might prefer it kick in with extra cooling when needed, I don't know yet :p
     
  8. Spike88 macrumors 6502a

    Joined:
    Jan 25, 2010
    #8
    Dummy light configuration is what they put into a typical Vehicle. re: Red TEMP dash light comes AFTER the vehicle is over heated. To me, all vehicles need a temp needle. Something that shows range and when temp is climbing higher - one a proactively do something about it. To me, iSat Nano is a good needle "proactive" app to proactively check internal heat.. Some folks say to drive an iMac until it over heats and automatically shuts down. If it goes so hot that it automatically shuts down, then its the same thing as a red temp light on a vehicle. re: "too late - internal damage is already done...".

    .
     
  9. MythicFrost thread starter macrumors 68040

    MythicFrost

    Joined:
    Mar 11, 2009
    Location:
    Australia
    #9
    Ah all right, I see, I've got all fans spinning at 2.1k RPM which isn't too bad, and the temps are good, HD 55, CPU 41, GPU 55/54, optical drive/mem controller 49, I could push them down even further with faster fans, I tried it once :p

    Am I going to wear the fans out much faster or possibly have them break off and do internal damage if I go say even at ~5k RPM? or is it safe?
     
  10. TMRaven macrumors 68020

    TMRaven

    Joined:
    Nov 5, 2009
    #10
    For me, too fast is whenever I can start hearing the fans over their default audibility, and that's 1300rpm for the gpu, stock everything else. However when I game under windows, the threshold is a bit higher since the game sounds and music will cover up some of that. I set the fans at 1400rpm for all components.
     

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