Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

MacBook Air 13 Over-enthuthiastic Fan

M

mac82

macrumors member
Original poster
Jan 17, 2011
54
1
Greetings. I've been enjoying and finding quite useful these forums for a number of years, and regret that my first post must concern a possible problem with a computer I absolutely adore. And to those who might say I'm nitpicking, and to not bother forum members with paltry concerns, please understand that some of us are not given computers by our parents; we work very hard to afford them, and become justifiably concerned with any signs of a possible problem, especially in the first two weeks when return and exchange are still possible. So, after that rather lengthy preamble, the point.

I bought the base model 13" Air a week ago, and have to say it is the zippiest and sleekest computer I have ever set eyes or hands on. It seems much faster and more capable than the MacBook Pro it is replacing. I have noticed, however, a phenomenon that has not occurred with either of my previous MacBooks: after maxing the CPU for a few minutes with Handbrake or some other intense activity, the fans don't even begin to reduce in speed until the CPU temperature reaches 48C, and take ages to settle back down to 2000rpm after working at 6000-6500rpm. On average it takes between 3 and 4 minutes. In my previous Macs, and in those of my friends and family, as soon as CPU load returns to normal the fans immediately spin down (there is no delay until a certain temperature is reached), and reach 2000rpm in less than a minute and a half.

For those who have a version of iStat (Pro, Menus, Nano), could you please perform an experiment with your current generation Air (13 or 11). Tax your CPU with something intensive, until the fans have been spinning at over 6000rpm for a few minutes, and then time how long it takes for 1) the fans to begin dropping from 6500rpm, and 2) the fans to reach 2000rpm.

I apologize for this long and rather rambling post, and hope that some of you very knowledgeable people can help determine if this is an anomaly with my computer, or if it's common to all new MacBook Airs.

Thanks, guys.
 
That actually sounds about right. The fans do tend to keep running a bit after the CPU load drops, after a longer session of them being used. To a degree, I think it is done on purpose as a precautionary tactic. For me, Minecraft is the easiest example for me to use. Why? Because other, bigger games, use quite a bit of hardware video acceleration and end up taxing the CPU a lot less. Minecraft seems like it is practically CPU only.
 
I just picked my MBA up yesterday. Same model as you the base 13.3" and mine was the same way.

Temps seem to get up there easy too.
 
This happens with my 13" MBA as well. It takes awhile before the fan kicks in but when it does, then it keeps going for couple of minutes.
 
Fans are not related to CPU load, they are related to heat. Once your CPU/chipset temps get up there, they won't come back down instantly because you've somehow stopped taxing the CPU, it'll take some time.

There is nothing wrong with your computer.
 
Did you guys really expect to own a laptop this thin and maintain the thermal characteristics of a typical laptop? There is far less cooling material (heat sink) in addition to having a smaller fan so to get around that it has to spin faster and for a longer period of time.
 
True. Fans are indicative of total machine heat, not just the CPU. We know that. However, in the MBA, the GPU seems to run way cooler than the CPU. It's almost precisely inline with CPU load when the unit heats up and starts the fan. So GPU-using games, with less CPU load, like Starcraft 2 run cooler than high CPU-using games like Minecraft.

Anyway, I did the test with a good session of Minecraft, just to maintain heat levels. Upon shutting down the game to just using a Web browser, the fans took a little over 2:30 minutes to spin down and stop. It stopped at around 2 minutes 45 seconds.
 
SC2 is a very heavy CPU game. CPU will be near 100%. It uses CPU for a lot. GPU will obviously also be taxed to max.

Fans on 13.3" are a lot louder than I thought they would be. Things like flash will set them off and they are extremely loud.
 
Kind of. I use the ultimate 13", and with the settings I use, it does use some CPU, but it's a lot slower to heat up than Minecraft. It gets up there, over time, but Minecraft is revving those fans very quickly. Minecraft, overall, is a way less intensive game, no doubt. However, it's lack of GPU acceleration throws a lot of everything at the CPU. So in a way, it causes the unit to heat up faster and activate the fans. It also seems that fans spin down a bit faster after a Starcraft 2 session.
 
foiden said:
True. Fans are indicative of total machine heat, not just the CPU. We know that. However, in the MBA, the GPU seems to run way cooler than the CPU. It's almost precisely inline with CPU load when the unit heats up and starts the fan. So GPU-using games, with less CPU load, like Starcraft 2 run cooler than high CPU-using games like Minecraft.

Anyway, I did the test with a good session of Minecraft, just to maintain heat levels. Upon shutting down the game to just using a Web browser, the fans took a little over 2:30 minutes to spin down and stop. It stopped at around 2 minutes 45 seconds.
Click to expand...

You failed to understand my post. CPU load has nothing to do with fans. CPU load causes heat. Heat is what starts up your fans. Just because your CPU load goes down doesn't mean your CPU gets instantly cooler, and as such, the fans continue to spin until the unit is cooled down.

Did you really think shutting down the game would make the fans turn off ?

Think of it like a kettle. Put cold water in and put it on the heater. Bring it a boil. Does the water cool down instantly as soon as you remove it from the heater ? Of course not, it takes time, otherwise there would be no such thing as hot tea or coffee.
 
I think he was using the logic of higher the temperature the longer it takes for the heat to go down at full fan speed.
 
Surface???

I wonder is THE laptop sitting on your lap or a cool flat surface??
My findings with several different laptops is that this can greatly influence the fan behaviour. Stick it on a cool flat surface.
 
As others mention, CPU load creates the heat, the fans react to the temp, not the load directly. Once you stop any CPU intensive it is going to take a few mins to cool everything back down.

To each his own but running something like Handbrake on a MBA is counter productive imo. Any program that will push the CPU to 100% for sustained periods of time needs proper cooling. While the MBA "can" do it, I personally would not push an ultra portable such as the MBA to do the heavy lifting of these types of programs.
 
size100 said:
I think he was using the logic of higher the temperature the longer it takes for the heat to go down at full fan speed.
Click to expand...

Yep. That's the logic I was using. I basically answered that it was normal for the time of the fans to run for a bit after the CPU load goes down. Just that I used Minecraft over something like Starcraft 2, because it generates more heat than Starcraft 2 faster. The best way to generate the heat is to use a CPU intensive program over one that shares the graphics load on the GPU. If both programs are demanding, the CPU-only version generates more heat. This is also similar to the Flash thing. Run the regular flash distribution, which doesn't have the extra hardware acceleration over the the new beta, which has the hardware acceleration. The one without hits the CPU more and generates more heat. The GPU-enhanced version will lay off the CPU some, and for the same video the fans either run lower or not at all. So obviously the GPU taking on the slack, maintains a relatively cool temperature, while the CPU works less and also keeps the temperature lower.

The only thing I've mentioned, in my observations, is that the CPU seems to be the main part generating the heat.
 
Thank you to everyone who responded to my post. I've been a bit worried that I bought a machine that may provide less than stellar performance when running Lion, given that it has only 2GBs of memory; it's good to know that I don't also have to worry about faulty hardware.

@iPhysicist: I don't actually mind the fan coming on (it's less high pitched and annoying than my previous macs) so smcFanControl isn't necessary.

@ugp: Great machine, isn't it? Mine runs much cooler than the MacBook Pro it's replacing. The CPU never gets above 85C, and the bottom is never more than warm.

@2IS: One never knows what to expect with Apple; they keep surprising us. :)

@foiden: Thanks for testing out your machine. You've reassured me.

@KnightWRX: Thanks for the response. I wasn't stating that I expected the fans to immediately fall back to 2000rpm; only that as soon as CPU load zeroed the fans should begin to spin down, as they did in both of my previous MacBooks, and in those belonging to pretty much everyone I know. What's out of the ordinary with the Air is that the fan seems to wait one and a half to two minutes after CPU load zeroes to begin cycling down, and then it takes another couple of minutes to reach 2000rpm. But, since the consensus seems to be that this is normal for these machines, I can stop worrying about it. :)

@matspekkie: I find that so long as I don't block the upper left corner of the Air, where the vent seems to be, it maintains similar temperatures on my lap as on a table.

@bossxii: Agreed. I only used Handbrake on the Air to stress test its CPU. My older laptop, though sluggish in every conceivable way, has a CPU better suited to such endeavours.

@Canadiandad and aberrero: Sounds interesting. I'm curious to know what sort of temperatures you get with and without CoolBook running when watching 720p YouTube videos, for instance.
 
aberrero said:
Coolbook makes it run really cool, I love it. Totally worth the ten bucks.
Click to expand...

does coolbook require the user to configure the temp, speed etc or does the program do that itself?
if it is user controlled how do you know what the optimum settings are for it to be a) cool (not as noisy)
& b) the settings you edit will do long term damage
 
barebackbadger8 said:
does coolbook require the user to configure the temp, speed etc or does the program do that itself?
if it is user controlled how do you know what the optimum settings are for it to be a) cool (not as noisy)
& b) the settings you edit will do long term damage
Click to expand...
You configure the voltage your computer will use. My 1.4 GHz is set to 2 modes, 700 MHz @ 0,8750 V and 1400 MHz @ 0,8750 V. So my computer switches between these modes dependent on the cpu load.
0,8750 V is below default, hence my computer will produce less heat and the fan not kicking on as much.

Optimal settings for most people is just to drag the voltage to the bottom, if you need higher voltage your computer will shut down and then you can just increase the voltage a little.

Notice that you are only changing the voltage, not the MHz, thus it will not be slower.

This is by FAR a better solution than SMC Fancontrol that just decreases the fan speed thus making the computer hotter.
 
Don't use SMC Fan control or coolbook or anything like it unless you want to take a chance on destroying your MBA.
 
DarwinOSX said:
Don't use SMC Fan control or coolbook or anything like it unless you want to take a chance on destroying your MBA.
Click to expand...

Perhaps the wise one can explain how lowering voltage is going to destroy the laptop? I'd love to hear this.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back