Macbook pro 15" late 2011 won't spin up fans

[carbonatd]

I have a 15" Macbook Pro, aka MacbookPro8,2, aka Late 2011 model. 2.4ghz i7, and 16gb of RAM.

I do lots of work in Photoshop and Illustrator, sometimes running filters or plugins that will peg both my CPU and GPU for 10-20 minutes at a time. Up until last week, any time my CPU or GPU were under load, the fans would spin up. Depending on the task, they would get up to around 6,000RPM as measured by iStat pro. This is normal and acceptable to me, as it drastically lowers my temps.

However, as of last week (4-16-13) my fans stopped spinning up. They seem to stay at a constant 2,000 rpm no matter what I do. Meanwhile, I notice my CPU/GPU temps getting dangerously high (90c-100c). My system will start to chug and slow down as a result of the high temps.

I've done lots of googling, and I've reset my SMC at least 10 times, with no apparent results. I can confirm my SMC resets, as my maglink charge light will change from orange to green and then back to orange as soon as I do it.

I know there are third party apps that can enable fan control, but none of them seem to do it automatically, nor do they provide the kind of management the default OS X fan control does. I've tried the system pref, Fan Control, but this only monitors CPU temp and not GPU. I've also used the SMCFanControl App, but this only allows me to set the minimum fan RPM, and my fans are still unresponsive unless I crank them up manually.

Does anyone have any suggestions or ideas as to what has caused my fans to suddenly stop responding?

Here's a list of things I have tried:
SMC Reset (~10 times)
Reset PRAM
Single user boot (FSCK -yf)
Safe Boot (permissions repair) 4 times
Repaired permissions from user account (at least 5 times)
Extended Apple Hardware test (no issues found)

This seems to be an error that effects all users of this machine, and not just my account. I am thinking a KEXT or system file has gone corrupt, but I can't seem to find any info. Otherwise, it could also be a sensor, although iStat and Temperature Monitor report all of my sensors are functioning just fine, and if those apps can read my temps, I am wondering why OS X can't. The Apple Store has been unhelpful, since there is not an issue with my motherboard and the system functions perfectly. I have been considering reinstalling the OS, but I have read on other forums that it won't fix anything.

Any ideas?

Thanks!

 

[dusk007]

Are you giving them enough time. The fans ramp up slowly with some delay that imo is almost a bit dangerous at extreme load. It is basically because fans that ramp up too quickly get annoying with only short burst load.

What does the Intel Power Gadget say about clock speeds?
Does it confirm throttling?

In theory the OS shouldn't be responsible. It only gives command but the smc is more or less independent.

 

[Doward]

Just to clarify:

1) Fans sit @ 2000rpm
2) Fans will spin up higher if you manually push them up via third party app

If that's correct, then something in the circuit controlling the fans is clearly bad. I'd think a faulty temperature sensor, since you've already reset the SMC.

 

[alphaod]

Take it to a store or call Apple. I had a similar issue. Turns out one of my fans was faulty.

 

[carbonatd]

Ok, after doing some more testing, it looks like my fans do spin up eventually, but they only seem to spin for CPU temp, and not GPU temp. I've read that operating a GPU or CPU at over 80c can cause damage, and I have experienced kernal panics or forced shutdowns as a result of running at 90c. It also appears as if my GPU sensor is blown, since the CPU temp seems to be the only thing that will trigger a fan spin up.

The Apple Store has already examined my laptop twice, and claims that there's nothing wrong with it...

 

[Queen6]

As a rule if there is a sensor issue, the fans do the opposite and spin up to maximum. As for the cause, if the system is passing the hardware test, then software is the likely culprit.

If you are looking for a third party app to control temperature try UltraFan it`s fully automatic just need to enter the required value a good starting point is 65C, right now UltraFan is the very best app for OS X temp control...

 

[carbonatd]

Does it monitor GPU temp? I've noticed most fan control apps seem to be cpu centric..