Hi fan rpm's on iMac

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This may be a dumb question, and this may not be the right place to ask, but it seems that I'm getting really high RPM's for the fans on my iMac; 27" quad core i& mid 2010, 12 GB RAM.


I run parallels for my work, with windows 7 as the OS. I noticed, especially when using Parallels, that the fans eventually run high rpm's: the CUP fan around 1700 or so, maybe a bit higher at times. Eventually at always goes up when I'm using it.

And just now the optical and HD fans were over 1000 -- around 1100 or so for the optical fan, and 1300 for the HD fan.

The power supply 2 temp also changes, but that may be normal, since I don't know how that works.


I have istat pro to monitor all this.

This doesn't seem to have happened before, and i was just wondering if maybe I've got some kind of virus that causes this.

Now I'm not an expert when it comes to this stuff, and I know that the fans will run higher when you use the machine, but it just seems to me that it could be possible that something else would be causing this, something that shouldn't be there and makes things work more than they should. When I just have the machine on and using, say, Safari and nothing else, the CPU fan RPM is around 939-941 (which I guess is the normal kind of 'idle' speed).

in my iStat pro, even with windows running, the CPU use by the User is 10% or so and the "System" portion of it is maybe around 4 percent or so, with the idle portion being somewhere around 86 to 88 percent. I just thought that with that much of the CUP being idle that it wouldn't be taking the machine that much to cause the fans (most notably the CUP fan) to run so high.

Even when I shut down paralells the fan still runs kind of high (around 1300-1500 rpm or so, maybe higher).

So I'm just wondering, since as I said this doesn't seem to have happened before; and I'm not sure if I had this problem before I went to Yosemite from Snow Leopard.

Could there be a virus problems or something, maybe something I got online?



I'd be happy to post a screen shot of my istat pro, but I don't know how to do that or if it's even possible.

Has anyone else experienced this?
 

Raz0rEdge

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Don't worry about it. Anything that stresses the CPU/GPU is going to cause them to generate heat, when the generated heat exceeds certain thresholds, the cooling system within the iMac is going to run the fan at varying speeds to control them.

When the temps reduce, the heat will reduce and in turn the fan speed will reduce.

This is all normal and exactly how it's supposed to work..
 
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Okay; thanks, but what concerned me as well is that when I close everything the fans still run high; they may slow down a bit, but just this morning, for example, when I closed everything and let it sit there it was still running around 1500 rpm; it seems that I have to put it to sleep, and then wake it up to get things down again.

But then again -- I woke it up from sleep, but changed the power setting so that it wouldn't and let it alone for about 45 min-1 hour, and the fans are at normal 'idle' speed. I suppose that it might take a bit of time to cool down. Just wondering.

Is there any way for me to tell when something is going bad or needs to be replaced? Is there any kind of 'normal' temperature for the CPU, HD, GPU diode, power supply, etc, to run at so I could maybe see if something's about to go?

I don't use my machine very heavily, usually only a couple of apps at the most at a time, so this is why I was concerned as well, especially since I've got a Processor that's more of the high end for the iMac.

What I mean to say is that I'm familiar with the temps for various parts of the machine, and it just doesn't seem to be abnormal, which I thought might cause the fans to run as high as they do; especially since the CPU didn't seem to be taxed too much as far as the amount of it that was idle.

Thanks for your response.
 
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Raz0rEdge

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I really wouldn't pay much attention to the speeds or anything, the machine is smart enough to do the right thing..

I use VMWare Fusion on my rMBP at work and have 2 VMs running at all times. When the machine is largely idle, the CPU temp is around 66-70C. Once I get a build running either VM, the temps will get up to 98-100C and the fans will kick in to control that..

Right now, the two fans in my system are running around 2300 RPM. At the higher temps, they will rev up to 6000+ RPM and are definitely audible, but then so is the heat being generated which I can feel with the aluminum case of the rMBP.
 
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Raz0orEdge:

One follow up, if I may. the machine has been running 'regularly' with Parallels for the past hour. I stat pro says the CUP usage is between 98 and 95 % 'idle.' I also noticed that the number of page outs is 385,458; where as before it was 4.5 million (not sure what a page out is), in addition the temps are lower (which probably has something to do with the CUP usage and I'm guessing the Page ins/outs as well)

Just curious -- any idea what might cause this difference between now and before? I haven't done anything. Strange -- not abnormal -- but strange; just thought it would be more consistent.

:)
 

Raz0rEdge

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If the machine is largely idling (95-98% indicates that) and the temps are steady at whatever is normal for your environment and the fans aren't going full bore, then that's perfectly fine..

Page Outs are directly related to the amount of memory you have. If you have say 16GB of mem and you've give your Parallels VM 6GB, then OS X has 10GB to play with. If you use memory intensive applications on the OS X side, once you exhaust available memory, OS X will start to page out unused memory blocks to the disk to make room for the new requests. When the app that had its memory paged out wants to use it again, they get paged back in from disk to memory. So the Page Outs and Page Ins indicate how much of the disk you are using.

A large number of Page Outs/Ins means that you should look to upgrade your total memory..
 
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What is the ambient temperature? Summer is not a good time, neither is an overheated house in winter.

Seems to me that Yosemite could be adding to the load.

Be warned that this could be leading to hardware failure. Heat stresses everything, and can open up solder.

I completely lost an iMac to heat. First I had problems with the CPU, then the GPU and finally the HDD.

Put your hands near the vents, it should be quite warm but tolerable. Possibly the heat sensors may be going as well. They used to just be dangling inside near the things they were supposed to monitor, if they drifted away they could only pick up the heat after it had already got quite hot and hard to manage.

Vacuum out any vents and take it into Apple to check out.
 
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Yeah, the kind that sucks.;D

Just suggesting you get rid of any accumulated grot that maybe blocking up the airflow.
 
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I appreciate the humor, but I meant that would it be all right to use a regular floor vaccum with a special attachment, etc, or a hand held vac?:)
 
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Yep, either sounds good to me!

Suggest you do it with the Mac unplugged.
 
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Yep, either sounds good to me!

Suggest you do it with the Mac unplugged.


If using a household/built-in vacuum to clean a Mac, especially if it's unplugged, keep your body grounded or keep touching something that is, and keep hold of the metal vacuum end. That fast moving air can generate a LOT of nasty static that needs to be drained off. ;)
 
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Far better if you can use a vaccum cleaner with a rubber suction nozzle.
 
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Far better if you can use a vaccum cleaner with a rubber suction nozzle.


Yes, but still keep hold of the metal end to keep things grounded. Rubber and plastic ends insulate.
 
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Try resetting the SMC. It keeps settings stored for things like fan speeds. It's possible it got corrupted.
https://support.apple.com/en-us/HT201295

EDIT: BTW, you said you are using iSTAT Pro. You didn't happen to enable the option it has to set the fan speeds? Click on the menubar icon; hover the mouse over "Active Set". It should be set to "Off".
 

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