Thanks a lot for all your instructions, I have done 3 more SMC resets with no result, the fans starts right from the beginning at full RPM, even before the desktop is loaded.. my activity monitor does not report any cpu usage over 10% in TOTAL! I have trashed the preference file you mentioned, nothing, so now i go for a Hardware test, as WWWZ suggested. sorry for being a pain, guys. My fan is spinning and spinning... and i am learning and learning...
René Bijloo wrote:
Thanks a lot for the corrections. The only hot spot alert i get from the gauge is about the cpu diode sometimes at 111 ºC, but now it is 7 ºC !!! and the fan is running and running noisily.
I go for the hardware test, man! or for a brandnew iMac?
CPU diode at 111C? But now at 7C. Did I get that right??? What gauge? Get iStat pro.
http://www.islayer.com/apps/istatpro/ (temps+fan speeds)
or Temperature Monitor (very accurate but doesn't show fan speeds)
Might need to run the HW test several times in Extended. It's not known for picking up errors that well, so getting no errors isn't conclusive. But if it finds one it can be trusted.
I am sorry to hear that you are still having issues.
Please ensure that you have done the SMC exactly as per Apple's instructions. Do not do anything other than what Apple recommends for your model. If you've done this there is no point doing it over and over again. To be brutally honest, Apple recommends this be one of the last steps to try actually.
If the AHT (Apple hardware test) has come up negative, let it run in loop mode overnight. To run in loop mode use control-L and let it run overnight in another room, it may pick something up. If I am not mistaken, a sensor error usually has an SNS in its string.
A bit of background, all macs have temperature sensors that connect as it were, to the SMC, which is a small computer of it's own in many ways. The temperature readings are passed on to the SMC and in turn the SMC regulates the fans according to temperature readings, of course the SMC has to have settings or thresholds set their defaults. If those thesholds are incorrect it will trigger fans incorrectly. This is only one of the SMC's functions by the way. It is very important that you run software update to ensure your mac is not missing any firmware updates which if absent may be responsible for the issue.
So, the SMC may be damaged or a sensor is damaged. Either of these are hardware related. Obviously there will be an associated cost for repair but this will depend on the components/labor needed to repair this.
As noted by a previous poster, it is true that AHT does not pick up everything, this can be expected. AASPs and Retail Stores have more robust service diagnostic tools to help diagnose issues.
Please note, the importance of testing against an external HD with a clean copy of the OS is to rule out any software you may have installed but forgot about. I know that there are software packages, which I would never recommend, to help control fans at the user level. This should be avoided. If you installed anything like this, remove it of course.
If you leave your mac off overnight and it turns on and fans just pick up at ful rate just after starting up then the SMC does not have it's setting to default or a sensor is delivering the wrong information to the SMC and the SMC reacts accordingly but incorrectly, blasting the fans.
In conclusion, if the above yields not positive results I would recommend the mac be evaluated for a potential hardware issue, whether to go forward with a full repair beyond the evaluation is an economic question that only you can best answer.
Do backup your data before anything else.
PS don't worry about asking questions, that's what this place is for and I for one am delighted to offer my help.
From the symptoms you provided here I would think there is a faulty sensor or the SMC settings are askew. For a cold boot you know the temperature is low so no need for temperature reading software anyway because Apple does not document what temperature your computer should run at. There is no public article that officially states what the operating temperature should be for any one model because mileage vary's depending on the load so using observations are best. For example, leaving the mac to cool and then turning it on guarantees a known ambient temperature.
Sounds like a sure hardware problem.
Doing the SMC Reset as I instructed will cause no harm. And it has been noted in this forum on a number of different occasions that several SMC Resets were needed to solve an SMC related problem. It may or may not be needed or even accomplish anything, but again there is no harm in repeating it.
If you are referring to smcFan Control, I think we should wait to find out if the OP has in fact installed that or any other fan program. However, I should point out that smcFan specifically -- which is what I use and can recommend (but certainly not for this occasion), if used properly and conservatively, will do no harm. Quite the opposite, it may prolong the life of the hardware. The only probem it may cause if not used conservatively is premature failure of the fan motors. But fans are much cheaper than drives, power supplies or logic boards.
I also wouldn't offer the recommendation to automtically install any Firmware updates (or any updates offered by SU) until I had checked out just what that update, if offered, was supposed to accomplish. Once installed, it is virtually impossible to back out of a Firmware update.
However, I won't get into a debate with someone who has already offered, among other questionable things, the completely incorrect recommendation to remove the PowerManagement.plist as a possible solution to this issue.
Yes, you are right, it is the GPU diode (i am new to all this terms) An alert of the gauge showed up telling it was at 111 ºC but after a while it said 7 ºC and now, today, it is at 7 ºC! The fan starts right form booting the machine, at 30 ºC. It has been running for hours now. I will do another 3-4 SMC resets counting exactly 15 / 5 secs. and also press the button afterwards 5 secs with the power cord unplugged for the ions...i fear you guys are making some kind of weired experiment with me...please do not ask me to drown my iMac in the bathtub to cool i t down...
CPU 0 Diode: 45 ºC
CPU 0 Heatsink: 45 ºC
CPU 0 Proximity: 45 ºC
GPU 0 Diode: 7 ºC
GPU 0 Heatsink: 45 ºC
GPU 0 Proximity: 46 ºC
Drive Bay 0: 58 ºC
Optical drive 0 Proximity: 46 ºC
LCD Monitor Proximity: 42 ºC
Power Supply Proximity: 52 ºC
Airport Proximity: 37 ºC
Hitachi HDS721010KLA330 : 60 ºC
ODD: 969 RPM
HDD: 2059 RPM
CPU: 3597 RPM
Average CPU: 49 ºC
Ambient: 24 ºC
Average fan 2126 RPM
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