Imac/air Cooling setup-arctic breeze


macrumors newbie
Original poster
May 18, 2012
I have a 2011 Imac 21.5 (the higher end model), I recently just bought this maybe 1.5 months for $1000.00, but this was owned for about 8-9 months from a previous owner. I dont know if this was from the previous owner or happened while i owned it, but 5 small grey lines (2-3inches, hardly visible) appeared on the top left of the screen (Inside the LCD, i took off the glass).

It doesn't bother me at all because i only see it in white background, not visible watching movies etc. My use of it is moderate with occasional gaming,SC2/portal, web browsing, and use Servetome (Use Streamtome app on Ipad/macbook air to view all videos/music, kinda like my own Netflix).

I've read all 50+ pages of the grey smudges thread, and i don't want that to happen to me so i though I'd share the setup.

First i use SMC fan control paired with istatpro to determine what fan setup to use, during normal usage it almost always stays at:
Optical 1050RPM
Hardrive 2000RPM
CPU 2000rpm
For torrents harddrive and CPU run around 2500-3000, optical 1000-2000 still experimenting...suggestions?

Second i have the arctic breeze usb fans specs:
4 2.0 usb hub at the base
fan attached on top
adjustable fan speed 800-1800RPM
LED knob
Bought 2 other usb fans to connect to it
Runs relatively quiet compared if i bought a fan small-medium fan.
Fan w/o usb dock run at a constant 1700 rpm visit neweeg for more info. Pictures are atteached.

That fans sit on twelve souths Back Pack. And no the fans are not directly blowing inside. The third fan pointing down to the desk is cooling of my 1tb blue silicone rugged Ext.HD

Before normal use(browsing,youtube, dl torrents(sorry guys i do F)
HD-140+ Gaming 140+
GPU Diode-150+ Gaming 180-190 Gaming for about 60-90min
GPU heat sink 150+ Gaming 180-190
all the other stats are about 5+ degree higher than you expect normal to be.

After smcfanscontrol and usb fans
SMC game settings, ODD 2200, HDD 3200, CPU 2200
HD-105-115 Gaming 110
GPU Diode-118-130 Gaming 135-145
GPU heat sink 115-130 Gaming 135-145
The backside is remarkably cooler under normal days. Gaming is the only time it gets warm, but never scorching hot as people have said.

Thats my macbook air sitting in twelve souths BookArc Air also covered in Zaggs invisible shield, I clamshell that a lot and connect it to my LCD 32" to watch movies(using the streaming app) HBOGO and sports on WATCHESPN.

After 30-45 min i could hear the fans blowing from a far distance, i stat pro said exhaust fans 3500-4500, ive seen 5000+ on 3+ hours of use, all the temps were well above normal. Plugged in one usb fan to the right where the power would be connected and everything back to normal and the exhaust fans were back at 2000RPM.


Last edited:


macrumors 65816
Aug 11, 2009
Using smcFanControl to have the fans run a tad higher than Apple programs them to isn't that pointless if you can stand the (slightly) increased noise level.
Apple tends to focus more on the machine being quiet than on the components receiving proper cooling.

Using fans to blow air onto the rear surface is pretty pointless. If anything, have them blow into the intake vents at the bottom of the iMac. This might, however, result in turbulences inside the iMac and thus more noise.


macrumors newbie
Original poster
May 18, 2012
Pretty pointless if you ask me, but to each their own.
i cant see how its pointless now that when im playing portal 2 for 90min
ODD 2000
HDD 3200
CPU 2200

GPU diode and heatsink is now 144-150F range
HD 115F
CPU 110F

Thats a significant difference without smc fan control and my usb fans, but like you said to each their own....just thought id share for people who maybe concerned about heat.
Last edited:


macrumors Core
Jul 24, 2006
The Ivory Tower (I'm not coming down)
just thought id share for people who maybe concerned about heat.
That's fine. The problem with most heat concerns is that they tend to be based on misconceptions. Reduced temperatures might decrease the fan noise or, if your computer is shutting down, solve an actual problem. For laptops it also might make it more pleasant to use on your lap. Past that, heat concerns are just based on misinformation and misconceptions.


macrumors newbie
Original poster
May 18, 2012
Reduced temperatures might decrease the fan noise
SMC control is set at a high fan speed, seconds before i start playing to keep the temps down so their already loud...i dont mind the sound because my volume is cranked up. i hardly hear the fans on my normal use setting. Is their a thread on misconception and misunderstanding on heat? or would you like to explain...

From my understanding on personal experience and reading through numerous threads(mainly the IMAC thread on grey smudges/heat/dust debate)....Imacs can get pretty hot and then have the fans kick in when the mac is already at high temps and the temperatures stay at that constant temp before it gets any hotter to avoid shutting down. I figure why not just crank up the fans before it gets hot and I'm able to achieve lower temps at a constant rate during use.

The usb fans help ventilate the warm air that use to just linger in the corner of my room (corner desk)...i understand how Imacs dissipates heat, why not just keep the whole back portion of the aluminum cool, instead of the bottom half....right??

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