MBA overheating: important new insight!

[Evangelion]

I have been on the overheating forums ever since the MBA came out. I have often pondered how a 20W CPU could get hotter than a 35W MBP cpu. I am beginning to wonder what the heat envelope of the GPU really is.

I don't have any numbers, but I would say that the NVIDIA-GPU in MBP runs a lot hotter than the Integrated Intel "GPU" in MBA does....

The thing you need to keep in mind is that while the CPU in MBA might run cooler than the one in MBP does, it's also housed in a a lot more tightly packed computer than the CPU in the MBP is. If you have more space, you have more room for the air to circulate and you can have bigger heatsinks and fans.

 

[Tom J]

...I am beginning to wonder what the heat envelope of the GPU really is. That would explain why things like DVD ripping do not drive the fan/stutter but playing video does. The MBA uses only one fan and one heatsink. Maybe the CPU is not at fault but the GPU is. I noticed previous poster had a similar theory. Now I know it may not directly explain core shutdowns; could be a separate defect or just that the GPU generates enough heat to impact the CPU.

The thing you need to keep in mind is that while the CPU in MBA might run cooler than the one in MBP does, it's also housed in a a lot more tightly packed computer than the CPU in the MBP is. If you have more space, you have more room for the air to circulate and you can have bigger heatsinks and fans.

And therein lies the crux of this issue. The rapid heating that users are reporting leads me to believe that the thin sheet of aluminum that serves as a heat sink doesn't have the mass to wick away the heat.

 

[n0de]

The GPU point is a really good one. The other part of the GPU is that it has the ability to throttle itself to save battery power. In windows there are user accessible controls to adjust this, not in OSX. I wonder if it's settings are too conservative.

 

[ayeying]

The GPU point is a really good one. The other part of the GPU is that it has the ability to throttle itself to save battery power. In windows there are user accessible controls to adjust this, not in OSX. I wonder if it's settings are too conservative.

If GPU's at fault, wouldn't 4 hours playing X2 - The Threat or Civilization 4 start causing the system to overheat, core shutdown, and all the other stuff?

 

[pughchrism]

watched this vid 2x - week 11 1.6/80g up to 80C, no stuttering, no core shutdown.

however i saw a core cutting in and out earlier today at ~ 69C w/you tube and with a lost high def episode playing full screen. at first the temp inched up to 84C w/no core probs but later temp dropped down to ~ 69C and intermittent core stoppage occurred at that low temp.

a core cutting in and out at such a low temp, think i need an exchange (bought saturday)?

come on pls, any comments?

 

[bjdraw]

come on pls, any comments?

This is the same thing I'm experiencing. No idea if it means the unit is defective.

 

[Eidorian]

* Last Modified on: January 29, 2008
* Article: 307297

Issue or symptom

3D graphics applications may be less responsive, or exhibit slow or 'sluggish' performance, when the CPU has been in heavy use for prolonged periods of time or in an extremely hot environment for a period of time.

This may happen if your MacBook Air is attempting to protect itself from overheating by shutting down one core of your CPU. In extreme conditions, the MacBook Air may also reduce the clock rate of the remaining core. Either protective measure may cause the application, especially 3D graphics applications, to be less responsive.
Products affected

* MacBook Air

Solution

To improve responsiveness in warm conditions, move your computer to a cooler area, or consider using a laptop cooling pad to dissipate the heat.

I'm just making sure that you guys know that Apple made a knowledge base article on this. I have no clue why they removed it though.

http://www.google.com/search?q=eidorian+core+shutdown

 

[bjdraw]

I agree, I think it is a GPU issue.

To anyone not having this problem, try this for 15 minutes.

Download any 720P h.264 video from Apple.com/trailers
Play the movie and under the view menu, choose loop, to get the trailer to play over and over again.

Open two terminal windows and type this command in each.
yes > /dev/null
(this does nothing more than drive processor utilization to 100%)
hit ctrl+c when you're ready to quit or close the terminal window.

My system can run without any issue as long as I want at full CPU utilization, as long as there isn't any video playing. If there is any video playing, then after about 15 minutes the system starts to lock up every few seconds. (A core doesn't always shutdown, but something it does. I'm not sure why this is.)

 

[Scott6666]

Fan?

I agree, I think it is a GPU issue.

To anyone not having this problem, try this for 15 minutes.

Download any 720P h.264 video from Apple.com/trailers
Play the movie and under the view menu, choose loop, to get the trailer to play over and over again.

Open two terminal windows and type this command in each.
yes > /dev/null
(this does nothing more than drive processor utilization to 100%)
hit ctrl+c when you're ready to quit or close the terminal window.

My system can run without any issue as long as I want at full CPU utilization, as long as there isn't any video playing. If there is any video playing, then after about 15 minutes the system starts to lock up every few seconds. (A core doesn't always shutdown, but something it does. I'm not sure why this is.)

You say it runs at full CPU utilization. I assume though the fan is pegged at 6200?

 

[JoeG4]

While it is true that they shrunk the CPU's packaging physically, the heat plate is still the same size, and the part that generates the most heat is also still the same size

 

[bjdraw]

You say it runs at full CPU utilization. I assume though the fan is pegged at 6200?

Yes of course, but the MBA runs as long as I want like this, as long as I don't have any video playing.

 

[SubZer0]

I agree, I think it is a GPU issue.

To anyone not having this problem, try this for 15 minutes.

Download any 720P h.264 video from Apple.com/trailers
Play the movie and under the view menu, choose loop, to get the trailer to play over and over again.

Open two terminal windows and type this command in each.
yes > /dev/null
(this does nothing more than drive processor utilization to 100%)
hit ctrl+c when you're ready to quit or close the terminal window.

My system can run without any issue as long as I want at full CPU utilization, as long as there isn't any video playing. If there is any video playing, then after about 15 minutes the system starts to lock up every few seconds. (A core doesn't always shutdown, but something it does. I'm not sure why this is.)

1st - I do not own the MBA, nor do I own a Mac.

HOWEVER, I am doing some research because I am soon to be a convert. SO, let me ask this - Is there a utility that measures the temp of the Graphics and Memory Controller Hub (GMCH)?

It sure sounds like the problem occurs most often when people play video, so if the GMCH is overtemping then maybe that causes the Core to shutdown. What do you think?

Mark

 

[droppedd]

GPU overheat

OK i'm pretty sure it's something GPU related, at this point. I'm on my second MBA (first one had even worse problems when cores would drop and cause lockups), and i can run "yes test" from a cold boot for an hour with no core drop... but once the machine is warmed up, running an HD trailer (or two, if you want to see it happen faster), or more tellingly running a Tremulous timedemo, causes a total core drop. Once the core drop happens, it's pretty quick to reproduce if you only let the computer rest again for a few minutes, but the temp of the CPU seems to have little or no bearing on when it happens. And being hooked up to an external monitor makes it happen quicker still.

I'll do a little more research, and if I'm coming up with reproducible results I'll upload my Tremulous files and instructions to test it yourself (i'd expect 10-30 minutes of playing any OpenGL based game would probably give you similar results, if anyone can confirm that). I might even do a wipe of my MBA tomorrow to test if the Leopard Graphics update might have something to do with it.

This would be a lot easier to test, also, if there was just a way to make XBench loop its openGL test infinitely... i might whip up an applescript for that, as it's much smaller and easier to run (although unlike the Tremulous test doesn't really test any real world application).

Basically it comes down to this: I want to be able to know I can plug my Air into my TV and watch a full-length H.264 movie I bought off iTunes, or that I can play a round or two of Quake 3. If a core drops and video starts to stutter after anything less than a few hours of doing that, at room temperature on a desk, then my $1800 air is just plain junk.

Core dropping should be protection in the case you're doing something outright wrong, like using the Air in 120 degree weather in direct sunlight, or blocking the exhaust vents with something -- it should never, ever, ever happen just because you're "working it really hard". I bought a dual core 1.6 ghz intel -- not an effectively 1.6 ghz single-core only usable as dual core when i'm not doing anything with the GPU.

 

[Maui19]

I have been having some overheating problems. Basically, when I view youtube vids for any length of time, the temp climbs, the fans max out, and the video stutters. The temp will stay high and the fans will stay on until I reboot the computer--even if I shut down all the apps and do nothing.

The interesting thing is this: I only get this behavior when my MBA is plugged in (even if the battery is fully charged before I start).

I'm taking it in to see the genius tomorrow.

 

[pughchrism]

droppedd

my week 11 1.6/80g is doing exactly the same thing. I did a clean install yesterday and then let it update. this made no difference.

core shutting down for 1 sec and then on for 2-3 sec at 69C when under load.

should i exchange for a new unit?

 

[bjdraw]

I just called Apple and reported the problem. The gentleman seemed very responsive and was very appreciate of my troubleshooting steps to reproduce the problem.

I suggest everyone call in and report the issue with the steps to reproduce the issue. The more who report it, the better chance Apple will take the reports seriously.

 

[bjdraw]

I'll upload my Tremulous files and instructions to test it yourself (i'd expect 10-30 minutes of playing any OpenGL based game would probably give you similar results, if anyone can confirm that).

Please do, I'd like to try to reproduce it.

 

[jont-fu]

I agree, I think it is a GPU issue.

To anyone not having this problem, try this for 15 minutes.

Download any 720P h.264 video from Apple.com/trailers
Play the movie and under the view menu, choose loop, to get the trailer to play over and over again.

Open two terminal windows and type this command in each.
yes > /dev/null
(this does nothing more than drive processor utilization to 100%)

Ok, I was interested in this issue and did the procedure.
1) First looped Speed Racer 720p trailer for 30min. Some programs running in the background (Azureus downloads, Safari). No stutter in video, cpu temp in the 60-65 range. Cpu utilisation about 50%.

2) Added the "yes > /dev/null" windows, maxing out the processor usage. CPU temp raised to 85C max, then settled back to around 75C. Kept this running for over half an hour. No core shutdowns (according to activity meter on dock), no stutter or noticeable frame drops. EXCEPT FOR: When Time Machine did it's hourly backup, the video playback dropped frames and stuttered occasionally. After the backup completed, video did run smoothly.

So, if I'm ever going to have an occasion where I need to simultaneously do some heavy calculation AND watch an HD video on my Air, I should turn off Time Machine. I guess it is a system process and takes precedence over user processes like Quicktime, and this causes the stutter.

YouTube videos take up about 40% CPU, which is only a bit less than 720p Quicktime! Last night I watched a 1.5GB DivX movie in VLC player which took only 20% CPU, and the fan kept silent all the time.

My MBA is 1.6 & 80, week 07 model. The only problem with this unit is a fault in the display panel (light spots "burn" momentarily on the screen), and I'm a bit afraid to take it back.. Will they take it in for a month to repair (I would miss my baby!), or will I get a new unit with possible overheating problem? Fingers crossed.

I really hope you get your overheating issues solved, and hope that my experiment was helpful.

Edit: I don't have an external display or TV, so couldn't test with them.

 

[ScottFitz]

I haven't done much research on this, but my experience with windows builds from previous years is this issue sounds like someones' doing some overclocking with the MacBook Air. Maybe when the OP clones his macbook, he used "normal" settings. When he reinstalled the MBA software, then maybe the overclocking settings returned?

Sounds like a GPU issue for sure if it only happens on videos. I've overclocked a lot of video cards in my days. Sure sounds like similar problems I would have when I was cranking a bit too high and had a bit too much heat to deal with.

 

[rom]

HDD intensive apps

Folks - try transferring files to an external drive and see how fast the MBA shuts down a core. Doing Time Machine with a large update also does this.

 

[ayeying]

Folks - try transferring files to an external drive and see how fast the MBA shuts down a core. Doing Time Machine with a large update also does this.

None. I have a time machine backup hooked up to my network at home. it's backed up every hour, on the hour as long as im connected to the network. I would be playing some games and it still wouldn't shut down a core.

Everyone's still missing the point, if it is a GPU problem, just test it in some games and it SHOULD happen regardless of what OS you're running.

 

[pgharavi]

None. I have a time machine backup hooked up to my network at home. it's backed up every hour, on the hour as long as im connected to the network. I would be playing some games and it still wouldn't shut down a core.

Everyone's still missing the point, if it is a GPU problem, just test it in some games and it SHOULD happen regardless of what OS you're running.

Peggle causes my core to shut down, sometimes faster than other times.

 

[bjdraw]

Ok, I was interested in this issue and did the procedure.
1) First looped Speed Racer 720p trailer for 30min. Some programs running in the background (Azureus downloads, Safari). No stutter in video, cpu temp in the 60-65 range. Cpu utilisation about 50%.

Thanks so much for taking the time to be our control! But just to be clear. You are saying the video plays back perfectly? No dropped frames? Because my 1.6/80 won't play 720p h.264 trailers without dropping frames, it isn't enough to bother me, but it does drop 'em.

2) Added the "yes > /dev/null" windows, maxing out the processor usage. CPU temp raised to 85C max, then settled back to around 75C. Kept this running for over half an hour. No core shutdowns (according to activity meter on dock), no stutter or noticeable frame drops. EXCEPT FOR: When Time Machine did it's hourly backup, the video playback dropped frames and stuttered occasionally. After the backup completed, video did run smoothly.

Interesting, I assume you are on the latest version of OS X? Your temperature does the same thing mine does, but mine does drop out after about 10-15 minutes.

My MBA is 1.6 & 80, week 07 model.

I really hope you get your overheating issues solved, and hope that my experiment was helpful.

What do you mean 07 model?
Thanks again for the help.

 

[droppedd]

itunes visualizer

OK - here's a good but realistic stress test... once the MBA is running hot, if i start an itunes playlist and turn on the iTunes visualizer in Large mode, resize it to take up most of the screen, then wait 30-60 seconds, a core starts dropping (at least hooked up to my external monitor), and within 5 minutes one core is just totally black.

Conditions: fully charged battery, starting with a warmed up MBA (fan already spinning at 6200 RPM, like mine always is once it's been on for a few minutes while plugged in to a monitor), plugged in to 1920x1080 LCD, keyboard, and external HDD. Clamshell mode, but with lid opened (that is, the built-in LCD is off but the MBA is open for better venting/air circulation).

I'll try it later tonight under "ideal conditions" (cold boot with no external devices or multitasking) and clock how long a core drop takes. One thing i'm noticing is that it's much harder for me to get a core drop when I'm not plugged in to an external monitor, though i'll test it both ways in "lab conditions" tomorrow night.

The advantage to this test is that it's testable on an out-of-the-box MBA, with no extra 3rd-party software required, and under a realistic task ("loop several HD trailers" can take a while and sounds weird to explain to a Genius). Try it with a quicktime HD trailer or YouTube video looping on top, or Google Earth in Tour mode if you want to really make it happen fast.

Is there anyone with this problem who has bootcamp installed who can check if the same thing happens in XP or Vista?

It's also possible that there's more than one heat issue in play here. A lot of parts in the Air are in really close proximity, so working the HDD really hard while maxing the CPU could cause the same sorts of problems (eg sometimes i get core drops with nothing but Transmission and YouTube)... but i'm finding it easiest to force with GPU-taxing operations. Let's keep working to make this as easily reproducible as possible. if anyone has other ideas, keep 'em coming.

 

[ayeying]

Peggle causes my core to shut down, sometimes faster than other times.

Well, since i'm on my lunch break and im bored, i booted into XP, fired up Sins of a solar empire and left civ4 running in the background, the system got insanely hot (the casing itself), cpu reads at 85 deg C both cores, yet, performance did not slow down 1 bit. Ran it for about an hour, still same performance. I highly doubt a little animation would kill one of the CPU cores when 2 high 3d games can't.