Brightness vs heat

Discussion in 'iMac' started by shardey, Nov 17, 2011.

  1. shardey macrumors 6502a

    shardey

    Joined:
    Jan 28, 2010
    #1
    Out of curiosity, how much more heat is produced by the LCD (early 09 24" is not LED backlight) backlighting at maximum brightness vs minimum? Anyone have any idea or any experimenting with this?

    I only ask this due to the fact my LCD looks like it has some marks from the heat dissipating from the exhaust vents.
     
  2. alust2013 macrumors 601

    alust2013

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    Feb 6, 2010
    Location:
    On the fence
    #2
    probably not a huge difference. I have never noticed my screen to get hot even at full brightness
     
  3. shardey thread starter macrumors 6502a

    shardey

    Joined:
    Jan 28, 2010
    #3
    Well from what I gathered, is regarding a laptop, the amount of battery that is consumed when the brightness is half vs full is pretty substantial.
     
  4. macdudesir macrumors 6502

    Joined:
    Jan 16, 2011
    #4
    Well, you may be looking for laptops, but here's my 2 cents. On my 27" iMac (2011) i notice that the brighter the display, the hotter the hard drive. it is a good think i don't mind having a darkish screen (1/3 brightness) because at full brightness, the Hard drive temp can reach critical temps. so in short, a defiantly noticeable difference.
     
  5. Icaras macrumors 603

    Icaras

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    Mar 18, 2008
    Location:
    California, United States
    #5
    I agree. Not sure about your particular model though, but yes, I definitely notice a substantial increase in heat when the brightness is turned rather high on my iMac.
     
  6. jsolares macrumors 6502a

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    Land of eternal Spring
    #6
    It's like 100W difference i think, so quite a lot
     
  7. shardey thread starter macrumors 6502a

    shardey

    Joined:
    Jan 28, 2010
    #7
    I wish I had the tools to monitor my Power consumption. Thanks for the replies as I did actually know there was a significant difference but 100W!? If the 27" LED backlit consumed that much more, I would imagine the 24" would probably be as high since it is lit by tubes.

    If anyone comes across any information, or performs a test of their own, please share. The difference of the brightness being turned down has already shown its affect on my temperatures.
     
  8. Dark Dragoon macrumors 6502a

    Dark Dragoon

    Joined:
    Jul 28, 2006
    Location:
    UK
    #8
    I just did a quick test of the power consumption of my old 20" Aluminium Apple Cinema Display using a power meter.

    The brightness range on it is not that great, though at minimum brightness it consumes 35W versus at maximum 61W.

    I usually leave this screen at around 90% brightness and it does get quite warm to the touch.
     
  9. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #9
    I'm not certain if it's relevant to later iMacs, but my Late 2006 wouldn't 'dim' below a certain point, other than "off".

    I found Shades allowed me to have full control over the backlight.

    http://www.charcoaldesign.co.uk/shades

    It sometimes allows the screen to go to full brightness, when launching some applications but not all.

    I've found it handy for setting a bare minimum brightness much lower than Apple's 'lowest' setting.
     
  10. Dark Dragoon macrumors 6502a

    Dark Dragoon

    Joined:
    Jul 28, 2006
    Location:
    UK
    #10
    I'm pretty certain Shades doesn't actually change the backlight brightness, all it does is change the brightness of the image sent to the screen.

    So the screen will still produce exactly the same amount of heat and the backlight will consume the same amount of power, no matter what brightness setting you use in Shades.

    Edit: Just tried out shades, going from maximum brightness to minimum brightness in shades and the power consumption of the screen stays exactly the same. Also by viewing a black image I can see that the backlight is staying at the same level.
     
  11. Big-TDI-Guy macrumors 68030

    Big-TDI-Guy

    Joined:
    Jan 11, 2007
    #11
    Late 2006 24" iMac gave you a very wide range of intensity.

    You can choose between staring-at-the-sun, almost down to staring-at-arc-welding. Why would anyone want to go dimmer? ;)
     
  12. MacTech68, Nov 19, 2011
    Last edited: Nov 19, 2011

    MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #12
    I never did any specific test when I first tried it. I needed a really dim screen for the room and Apple's lowest setting was like a beacon. Shades provided the solution I needed. Other than that I have the display set to auto off within 1 minute specifically to reduce the iMac temperature. Ineverters and CCFLs aren't all that "cool".

    I'll agree my post was mis-leading. That's not my intention. :(

    Have you tried the lowest setting in a completely dark room? Admittedly, mine is a 20", not a 24"
     
  13. InuNacho macrumors 65816

    InuNacho

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    Apr 24, 2008
    Location:
    In that one place
    #13
    How hot is your HD at max brightness and what is it doing while at high temperatures?
     
  14. Big-TDI-Guy macrumors 68030

    Big-TDI-Guy

    Joined:
    Jan 11, 2007
    #14
    This brightness problem is unique to the late 2006 24" imac, I have not seen it on any others.

    I've got a 2005 20", and that one is beautiful. Display on that one looks better than most of the new displays. I've seen it side by side with them - it really does.
     
  15. product26 macrumors 6502a

    product26

    Joined:
    May 30, 2005
    #15
    My battery backup has a screen showing the load. At the lowest brightness it shows 85w at the highest it goes up to 176w. HUGE difference!
     
  16. macdudesir macrumors 6502

    Joined:
    Jan 16, 2011
    #16
    If i put the screen to full brightness and browse MacRumors for about 20-25 min, the Hard drive will get to about 55-56C (131-132F). Right now, doing the same, but at 1/3 brightness, my Hard drive is at 44C (111F). The HD isn't the best cooled component in the iMac, thats for sure. Lol. ;)
     

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