When Should Higher Fan Speeds Kick In?

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bowjest

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Hello to all,

I've just been reading mail and some web pages and found my CPU temp jumped to 72C.

This seemed a bit high, so decided I'd load some more apps to see at what point the higher fan speeds should kick in.

I've loaded quite a few apps and got the CPU temp to 81C, but the fans have only gone from 1995 to 2215.

Is that right? At what point/temp should I actually hear the fans revving up to cool things down?

Thanks.
 
UPDATE: I've currently got iTunes open updating the OS on my iPhone, Thunderbird is open, but idle and Firefox is open, but idle. MBP is on a hardwood table.

I've not done anything with the computer physically for the past 15 minutes and the CPU temp is at 69-70C, fans are at 2006rpm.

Seems very high considering I was sitting yesterday afternoon with several apps open, MBP on my lap, actively working and the temp fluctuated between 49-59C.

Is the sensor out of whack or is something strange going on here? Makes no sense to me that the temp is lower when I'm actively working with the machine than when I'm not.
 
Your MBP has 3 thermal sensors.They're held in place by a small piece of double side tape! Quite possible that one or two have shifted or are starting to fail. causing your poor fan performance.At 70C fans should be over 5000 rpm.Take your MBP to an Apple tech and have it checked.
 
Thanks, oldmanmac.

I've just booked a genius bar appointment for tomorrow morning. I hope that whatever the problem is they can fix while I'm there as I can't afford to not have the use of my laptop - it's what runs my whole business! :(
 
One last thing: is there a chart somewhere that gives recommended fan speed values at given temperatures?

I'm just trying to reproduce what I outlined above so I can take a screenshot and show to the guys at the Genius Bar, but would also like to have a chart to refer to for the future.

Thanks.
 
UPDATE: Took my MBP to my local Apple Store and left it with the Genius Bar while they ran some diagnostics.

The tech told me they ran 6 iterations of some tests and the SMC/fans all checked out ok.

He went on to say that not all machines have their fans kick in at the same temp and he doesn't find 70C *not* causing the fans to rev higher to be a problem.

I guess that's all that can be done.

Any further suggestions would be appreciated.

Thanks
 
The MacBook Pros do run hot -- I don't see anything that you've posted that would be considered out-of-the-ordinary for that machine.

My Mac mini frequently hits between 160 and 180 degrees F without the fans turning much faster than 2,200 rpm. Some CPUs are rated for cooler operating temps, some are rated for higher operating temps. In my experience, mobile processors (those in laptops and laptop-like computers like the mini) run hotter on average than their desktop counterparts.
 
Thanks, Diablo.

Glad to hear that about the differences. I wasn't aware.

I'll just accept that this is the way it is while keeping an eye on the temp and fan speeds as time goes on.
 
Diablo,

I was just doing some PDF to text conversions with an OCR tool and notice that my MBP CPU temp has gone up to 91C and the fans are still turning at between 1990-2006rpm.

Does that still sound reasonable? It's pretty bloody hot, I have to say!
 
No, it is not in the least bit reasonable! At that temp the fans should be at 6000rpm.Next time it happens do a screen shot of your temp readings and save it! Book an appointment at the Apple store and show them and escalate to a supervisor if you have to.In the meantime set your fan control to max the fans out at 72c and see if that works.If the fans don't respond to fan control then it's more than likely you have a hardware issue.
 
UPDATE: I went back to the Apple Store yesterday and they re-installed the OS and opened up my MBP and cleaned some dust out of it (not much, they said).

I then stressed my laptop while in the store and got the temp back up to 91C. The fans, after several minutes, slowly rose to 4100rpm and a bit and the temp dropped back gradually to the low 70's (with the fans going back done into the 2000+rpm region).

Having said that, I had a runaway process last night that got the temp up to 95C and the fans were only just starting to climb into the high 2000rpm region when I killed the process and things settled down again.

Currently I'm reading mail (Thunderbird), browsing in Firefox and reading some PDFs and the temp is at 46C (and slowly rising) with the fans rising and falling between 1998rpm-2010rpm.

Does this now seem reasonable?

I said to the guy at the Genius Bar yesterday that although the values might fall withing accepted parameters, my concern was that they were not ideal and would ultimately shorten the life of my (very expensive) laptop. He said that in his experience the temp could go over 100C before the fans really started to kick in and besides, at 130C the machine would shut itself off.

Not sure that really reassured me.
 
I've recently been using Handbrake to create some videos to watch on my iphone at lunchtime while I'm at work from a series of free DVDs I got with a newspaper.

The conversion usually takes around 35 minutes and shortly after I start the CPU temperature hits 90C. Once the CPU Heatsink gets to 40C then fans start to increase in speed. I've watched the temp climb up to 97/99C and hover there, cooling down quite quickly after the conversion finishes.

I consider this to be quite normal as the previous laptop I owned got really hot and the fan/heatsink exhaust turned into a mini hairdryer when I performed any heavy-duty tasks.

I'm doing a test conversion on my 2.53Ghz i5 Macbook Pro. CPU temp is hovering around 95C with both fans running at 5000rpm.
 
As I explained before,use SMC Fan Control to turn your fans on quicker.Set them to go to max at 70c to help keep the heat down.
 
calamarain,

Thanks for your feedback. Over what period of time does it take for your fans to rev up to 5000rpm? Part of what concerns me is the amount of time it seems to take before anything starts to ramp up.

That and the fact that back in the summer when things go anywhere near 90C both fans were running like a hairdryer, but now the most they seem to go up to if a bit over 4100rpm.

If everything is being managed that is, of course, great - it just seems that things get very hot and stay that way for a significantly long period of time before the fans slowly start to increase in speed and things gradually start to cool down.
 
It only takes a few minutes for the fans to increase in speed. I suspect the fan control is a combination of CPU temp and heatsink temp according to some mystic formula. Faster fans in the summer may be due to a higher ambient temp, leading to less efficient cooling.
 
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