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Macbook Air fans - effects of constant high RPM?

onthecouchagain

onthecouchagain

macrumors 604
Original poster
Mar 29, 2011
7,382
2
So I have my Air set up with a Thunderbolt Display, and the Air seems to be constantly running its fans at high RPMs while doing perfectly normal things (browsing, playing music, etc). So not watching Flash, for example. They spin anywhere from 4000-6500 RPMs (6500 is the max), keeping the Air at around 50-60 degrees C.

The noise is a little annoying, but more importantly, what are the side effects of having the Air's fans constantly running and running so high? Do they wear them out quicker? Does it make the internals dustier? Etc?

If anyone knows about this, would love to hear about it.

Thanks.
 
This will surely cause the fans to wear out quicker, but I doubt it makes any difference for the amount of dust inside your machine.
 
onthecouchagain said:
So I have my Air set up with a Thunderbolt Display, and the Air seems to be constantly running its fans at high RPMs while doing perfectly normal things (browsing, playing music, etc). So not watching Flash, for example. They spin anywhere from 4000-6500 RPMs (6500 is the max), keeping the Air at around 50-60 degrees C.

The noise is a little annoying, but more importantly, what are the side effects of having the Air's fans constantly running and running so high? Do they wear them out quicker? Does it make the internals dustier? Etc?

If anyone knows about this, would love to hear about it.

Thanks.
Click to expand...
Try resetting the SMC.

The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C, GPU Tjmax = 100C on i3, i5, i7 processors. (Source: Intel) If you're not already using it, iStat Pro will give you accurate readings of your temps and fan speeds, among other things.

Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If you're constantly putting high demands on your system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just your Mac doing its job to maintain temps within the normal range.

It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.

Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level. If they're spinning up without increased heat, try resetting the SMC. (PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)

The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks. The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best.

Learn about the fans in your Mac
Apple Portables: Operating temperature

For Flash-related issues:
 
Even at high rpm's they will be fine. I take it your running clamshell mode? Temps will naturally be higher for two reasons. One the gpu is working harder, two the lid being closed stops the surface around the keyboard from venting how it normally would. I wouldn't worry this it's normal and safe
 
I'm running the same setup and I very rarely notice the fans at higher RPM. However, I installed the iMessages beta and for some reason, that seems to be causing the machine to run hot for me. Actually noticing the fan when I run iMessage. Hopefully this is just a bug and not foreshadowing of Mountain Lion. Skype will also make the fans spool up for me.
 
Gav2k said:
Even at high rpm's they will be fine. I take it your running clamshell mode? Temps will naturally be higher for two reasons. One the gpu is working harder, two the lid being closed stops the surface around the keyboard from venting how it normally would. I wouldn't worry this it's normal and safe
Click to expand...
While heat radiates in all directions and dissipates through all surfaces, there is no air intake or exhaust venting through the keyboard on any Mac notebook, and there never has been. Both intake and exhaust is through the vents in the rear near the hinge, which allows venting with the lid open or closed (for operating in clamshell mode). There is a solid panel under the keyboard, preventing any meaningful airflow.
WTBDHrUFidEXI1d4.large
 
GGJstudios said:
While heat radiates in all directions and dissipates through all surfaces, there is no air intake or exhaust venting through the keyboard on any Mac notebook, and there never has been. Both intake and exhaust is through the vents in the rear near the hinge, which allows venting with the lid open or closed (for operating in clamshell mode). There is a solid panel under the keyboard, preventing any meaningful airflow.
Click to expand...

When my Blackbook gets around 4000+rpm, I feel air being pulled in through the centre part of the keyboard. Not sure where the air is going, but air does move through the keyboard.
 
Intell said:
When my Blackbook gets around 4000+rpm, I feel air being pulled in through the centre part of the keyboard. Not sure where the air is going, but air does move through the keyboard.
Click to expand...
It doesn't, actually. You're feeling the draft of the air moving from the vents in the rear and hitting the screen. There is no venting possible through the keyboard, as it's sealed. You can look at all the photos from the iFixIt teardowns as proof, if you don't want to open your Mac to see for yourself.
 
The piece-of-paper-sticking-via-suction-test shows otherwise. I've seen the inside of my Blackbook's and the underside of the topcase and ssw few holes, but air does move through my keyboard. Just enough the hold a standard piece of printer paper when the Macbook is tilted at angles that should make the paper fall off. Even putting the paper along the top row of keys and against the screen to block hot air from the keyboard I still feel moving air being pulled into the top centre of the keyboard.
 
Intell said:
The piece-of-paper-sticking-via-suction-test shows otherwise. I've seen the inside of my Blackbook's and the underside of the topcase and ssw few holes, but air does move through my keyboard. Just enough the hold a standard piece of printer paper when the Macbook is tilted at angles that should make the paper fall off.
Click to expand...
That's not venting. If you look inside, both the intake and exhaust vents are in the rear, near the fans. There isn't enough air moving around or through the keyboard to provide any venting or cooling, and the design of Apple notebooks has never depended on airflow through the keyboard for cooling. If that weren't true, Apple wouldn't give instructions on how to operate in clamshell mode. Clamshell works because the vents are still exposed with the lid closed.
 
It's still air entering the machine from an external source that assists in cooling. No matter how little, having the machine open can reduce temperatures.
 
GGJstudios said:
While heat radiates in all directions and dissipates through all surfaces, there is no air intake or exhaust venting through the keyboard on any Mac notebook, and there never has been. Both intake and exhaust is through the vents in the rear near the hinge, which allows venting with the lid open or closed (for operating in clamshell mode). There is a solid panel under the keyboard, preventing any meaningful airflow.
WTBDHrUFidEXI1d4.large
Click to expand...

I know there is no physical holes but closing the lid adds another layer for the heat to get through.
 
Intell said:
It's still air entering the machine from an external source that assists in cooling. No matter how little, having the machine open can reduce temperatures.
Click to expand...
It's heat dissipation, more than any airflow, that is affected by having the lid open. If Apple depended on airflow through the keyboard for cooling, they would leave it open to maximize such airflow, instead of blocking it, as in this picture of the underside of the C2D MacBook keyboard:
4TQHvA2HDHx5wvJ3.medium
Gav2k said:
I know there is no physical holes but closing the lid adds another layer for the heat to get through.
Click to expand...
That's right. It's dissipation, not airflow that is affected by having the lid closed. Still, it's not enough to significantly affect operating temps.
 
The little airflow that it does allow does make a difference. For the few months that I used a keyboard skin on my Blackbook its idle and maximum temperatures was slightly higher than without the skin. The temperatures also rose faster and fell slower with it on as well. It does baffle me how the air works its way through the keyboard.
 
I have also noticed that the fans kick in much more often when the lid is closed while using my external Apple Cinema Display. I don't know whether it's bad for the computer, but the noise bothers me. So I always leave the lid open now and have the built-in screen set to low brightness.

My fans almost never run now, unless I'm doing something intensive like recording music in Logic for awhile.
 
Would it help to get a stand for the Air, so that the bottom is exposed? For example, the BookArc?

Thanks for the replies, all.
 
I noticed it's iTunes that bumps up the temps. Whenever I'm playing music, it goes up to 60-65 degrees C. Is it because the speakers are being used?
 
onthecouchagain said:
I noticed it's iTunes that bumps up the temps. Whenever I'm playing music, it goes up to 60-65 degrees C. Is it because the speakers are being used?
Click to expand...

No, the speakers don't generate much heat. The CPU and GPU are the two primary furnaces. Use iStat Pro to see which components generate the most heat.
 
Using iStat, it seems like it's almost always the CPU that runs the hottest.

Again, this is under normal usage. Browsing non-flash websites, playing iTunes, and having a few miscellaneous things opened (Calendar, Sticky notes, Dropbox... that's really it).

It seems to stay in that 50-60 degrees C range, and the fans anywhere from 4000-6500. Definitely audible.

I did a SMC reset already. (Not sure how to tell if I successfully did it. I shut down, pressed and held SHIFT, CONTROL, OPTION, and POWER for two seconds, let go, and hit the Power button again. It booted up normally. Don't know if I properly reset the SMC or not...
 
Intell said:
The little airflow that it does allow does make a difference. For the few months that I used a keyboard skin on my Blackbook its idle and maximum temperatures was slightly higher than without the skin. The temperatures also rose faster and fell slower with it on as well. It does baffle me how the air works its way through the keyboard.
Click to expand...

I can verify this. When I use the screen protector in clamshell mode, the Air runs about 10C higher, than without. So there is airflow through the Air keyboard.
 
Last edited:
The fans running so loud doing such basic things (ie. no flash) is starting to become a deal breaker. It's especially obnoxious at night when it's quiet and the fans are very audible.

Not sure what to do...
 
Is it running hot only when running the external TB display? I'm wondering if using a TB display causes an extraordinary load on the CPU?

I am running a 2010 13" Air in clamshell to a Dell 24" monitor using a DisplayPort cable, and it runs cool in the 50C range.

I just bought a TB display in anticipation of getting the MBP when it comes out, but not sure if TB displays are worth it if they are causing heat problems.
 
sorry this is not exactly ur case coz ur using a mba but I've noticed when I attach my 2010 15" mbp to my 24" external samsung monitor that the fans kick in earlier than usual

also when I'm using apps such as vmware to use windows stuff that the fans kick in more

could be because the graphics etc are working harder so more heat?
 
funkyc said:
sorry this is not exactly ur case coz ur using a mba but I've noticed when I attach my 2010 15" mbp to my 24" external samsung monitor that the fans kick in earlier than usual

also when I'm using apps such as vmware to use windows stuff that the fans kick in more

could be because the graphics etc are working harder so more heat?
Click to expand...
Yes, and also running virtual machines like VMware will consume more system resources, creating heat.
 
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