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Bumping RPMs question

Hello everyone and happy new year and happy holidays 🙂

So yes I am using smcFan i know its not all that good and people don't really recommend it but even so i use it at my own risk.

I just have a question about the fans in my 21.5" iMac the 2010 model to be precise. So constantly monitoring the temperature of my HDD and i reed about the HDD and how that piece of hardware is the most temperature sensitive. So my hdd under load goes up to 45 - 48 that is kinda the max with smcFan on of course.

I usually run smc fan a lot may not be the right word but mostly 70% of the time fans are at a higher RPM than usual.

Now can someone with some knolage please tell me how to set the RPM's for the fans and for how long to run them. If needed i will provide temperatures and other data.


Thank you very much.

Posted on Jan 1, 2012 12:07 PM

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31 replies

Jan 1, 2012 1:06 PM in response to R Tweaky

As you are going to find out, there are those that frown on it and those that use it.


I think that there is a fine balance here between good and evil.


On the good side, if you live in a hot climate with no A/C or other cooling, then smcFanControl can be used to help keep the iMac cooled down and actually extend the life of your hardware.


On the bad side, you are going to suck in more dust, lint and crud past the air intakes and into the fans instead of only collecting it on the outer grills.


With that I say, if you must use it..? Keep the speeds down to a minimum and shutdown (stopping the fans) every month or so and vacuum out the air intakes to keep it as clean as possible.

Jan 1, 2012 1:06 PM in response to R Tweaky

You will get different opinions on this. My take is that Apple has set the fan program in the SMC for quiet fan running (read "marketable"), not efficient temperature control. At 54 for the drive and 60 for the CPU the fans should ramp up. Eventually they will at even higher temps, but running like this long tern will slow roast the hardware. Don't listen to "purists" who insist that Apple must be doing this right. Ideally, you want to keep the drive under 45, although this may be difficult. 54, over time, will probably kill it. It's insane that the smc doesn't ramp the fans up when it gets that hot. I don't like to see the drive run for too long in the high 40's.


I use smcFan. There is nothing wrong with it.


Here's a thread with a number of screenshots of my settings and an explanation of how I use it. Scroll down a bit.


If you use smcFan prudently, you won't shorten the life of the fans and it will extend the life of the hardware.


https://discussions.apple.com/community/mac_os/mac_os_x_v10.7_lion?view=discussi ons

Jan 1, 2012 1:07 PM in response to WZZZ

Thanks den.thed very informative as well as WZZ.

Actually i was hoping that WZZZ will reply on this one 🙂 WZZZ can you please post a direct link on your post i did not manage to find it. and can you tell me if lets say i run my fans at ODD: 1249 HDD: 1524 and CPU: 1425 for how long should i run them at those RPMs and prevent premature wearing out?

If you want i can compile some info and post it about temps idle speeds maybe you can help me out on setting the fans to a good rpm setting the main thing that i want to keep around 45 if possible lower is the HDD.

Jan 1, 2012 1:30 PM in response to R Tweaky

Sorry, wrong link.


https://discussions.apple.com/thread/3219643?start=0&tstart=0


I have iStat Menus with the Drive and CPU temps, along with the fan rpms from smcFan, right in the menubar always visible. I use several different settings accordingly. During the winter I generally run at the setting "minimum minus" and, if needed, I turn on a small clip-on fan mounted to the wall behind the computer, aimed at the upper left (as you face the screen) of the back, which is where it gets the hottest. In the summer, I keep that fan running almost all the time. It really helps to dissipate the case heat and keep things cooler inside. But if I'm running that fan a lot, I will dust the back of the computer and the area around the computer frequently. And if it's really hot, as it was last summer with the indoor temp here in the low to mid 90s and high humidity, I just let the computer sleep much more often, or I just shut it down. Like that it's too hot to sit in front of a computer anway.


You really have to experiment with what works best for you. But, to avoid burning up the fan motors, stay in the range of + 200 - 500 rpms. Also den.thed's suggestion to vacuum periodically the lower intakes (along the center bottom and behind the stand) is great advice.

Jan 1, 2012 5:04 PM in response to R Tweaky

You mean it's 43 and the fans have stopped if you sleep it. Well, it's not all that critical. But, if you want, you could always sleep the display (CMD-Shift-Eject in Snow Leopard and maybe Leopard) first for a little while. The screen generates a fair amont of heat. If you sleep the display the fans keep running. 43 isn't that high and isn't going to roast anything though. As soon as you put it to sleep, if the room temp isn't too hot, it'll cool off quickly enough. It's running it at high temps long term that's the killer.


Again, the fan at the back for a few minutes helps a lot to cool it off after sleeping.


Just go ahead and put it to sleep.


Just to add one thing: I often keep the drive spinning up for long periods of time in cool weather with the display sleeping. Drive temps might be in the low 40s and with the screen sleeping it will cool down somewhat. I sleep the computer when I know I won't be using it for a few hours. But there are no hard and fast rules about this.


Message was edited by: WZZZ

Jan 1, 2012 5:00 PM in response to R Tweaky

43C is really not all that hot, however if the drive is sitting at 55C or above then it is probably a good idea to let the iMac sit with no activity for awhile before sleeping or shutting it down completely. Also note that sleeping the display for a short time before sleeping the computer or shutting down can take a lot of heat off the whole system.

Bumping RPMs question

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