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Fans running. FULL speed. Non stop. Not joking.

G

gjarold

macrumors regular
Original poster
Nov 14, 2007
123
0
Brand new 2009 octo, with the 2.2x ghz CPUs.

Turn it on, start NO apps. Let it sit idle. Within a few minutes the fans ramp up to FULL jet engine speed. I can't hear people on the telephone.

And never stop.

Let me reiterate that I am running NO apps. My load averages are in the zeros.

OBVIOUSLY I am doing something wrong. This is not normal. Please tell me what MY ERROR is.

Thanks.
 
I had the SAME EXACT problem on my 2008 octo. It was thst way since I took it out of the box for the first time, apple said it was the logic board. They just replaced the computer. Unfortunately mine was a CTO with AirPort, so I had to wait for it to come in the mail. Bring it in to an Apple Store if you can.
 
Install a program such as iStat Menus to show you the temperature readings of the temperature sensors in your computer. I'm curious what they are reading.

My friend has a problem with the sensor on his northbridge, the computer was reading it as 259 degrees, which obviously just can't happen. It put the fans at full speed and it continued to read 259 degrees, even though the northbridge was very cool to the touch due to the fans running at full speed.

My guess would be you have a temperature sensor gone bad and the system thinks it is overheating.

Can you tell which fans are going at full speed? That's another thing iStat Menus can help you determine, how fast the fans really are running.
 
My 2008 octo 2.8 is running at 499 RPM and 106 degrees 99% of the time. EVEN when doing multicore tasks and rendering.
 
Apple Hardware Test will be more detailed than anything else. And if you bring your mac pro into an apple store, this is exactly what they will do:

For Intel-based Apple computers shipping with Mac OS X v10.5.4 or earlier, Apple Hardware Test is located on the Mac OS X Install Disc 1 and should be included with your computer.

For Intel-based Apple computers shipping with Mac OS X v10.5.5 or later, Apple Hardware Test is located on the Applications Install Disc 2 and should be included with your computer.

Note: Please be sure to disconnect any external devices, printers, hard drives, scanners, and so on (other than the Apple keyboard and mouse) from your Apple Computer before starting up to Apple Hardware test and running the Diagnostic.

To start up your computer in Apple Hardware Test:

If the computer is already on, insert the appropriate disc into the optical disc drive, then restart. If the computer is not on, turn it on and insert the disc as soon as possible after startup.
Press and hold the "D" key before the gray startup screen appears.
It takes a minute or so for Apple Hardware Test to start up and inspect your hardware configuration. While this is taking place, an icon appears on the screen:

When the process is complete, select your language and click the right arrow. If you aren't using a mouse, you can use the up and down arrows to select a language and then press the Return key.
The Apple Hardware Test console appears. You can choose which sort of test or tests to perform:
To perform all of the basic tests, click the Test button or press the "T" key or the Return key.
To perform a more thorough diagnostic test, select the "Perform extended testing" checkbox under the Test button before you click the Test button.
Your test results will appear in the window in the bottom-right of the console.

The Hardware Profile tab of AHT provides specific information about your computer. To see this information, click the tab, then select a subject area on the left.

To exit AHT, click Restart or Shut Down at the bottom of the window. Remember that clicking Shut Down will not automatically eject the disc.
 
p.luik said:
Apple Hardware Test will be more detailed than anything else.
Click to expand...

Good call, he should run the AHT... but I do disagree with it being more detailed. The default AHT that comes with every Mac is garbage compared to the actual service diagnostics CD's that that Apple has. Those give you much more info. But alas, the general public doesn't have access to those CD's.

If AHT fails, I'd like to know what it failed with.. but even if it does or doesn't fail, doing what I mentioned with iStat Menus may give you some more insight as to what the computer is actually reading on each temperature sensor and fan speeds.

Oh, but one thing I'm not sure of is if iStat Menus supports the 2009 Mac Pro yet.

The AHT may be your best and only course of action at this time.
 
p.luik said:
The genius gave me the diagnostic disc in case I had any more problems. ;)
Should I be hosting a disc image so others can download it?
Click to expand...

The service diagnostics CD's generally only work in a few machines. So if you have one for the Early 2008 Octo 2.8, it won't work in the newer 2009 models anyway.
 
p.luik said:
I had the SAME EXACT problem on my 2008 octo. It was thst way since I took it out of the box for the first time, apple said it was the logic board. They just replaced the computer. Unfortunately mine was a CTO with AirPort, so I had to wait for it to come in the mail. Bring it in to an Apple Store if you can.
Click to expand...
Me too. I thought it was within spec and let it go from 5/2008 to 2/2009 when someone told me it was not right. After getting new CPUs, PSU, MLB, GPU, memory, and hard drives I was given an entirely new machine. There is no fix for this issue afaik. They called it a sensor issue ...

tobyg said:
Install a program such as iStat Menus to show you the temperature readings of the temperature sensors in your computer. I'm curious what they are reading.

My friend has a problem with the sensor on his northbridge, the computer was reading it as 259 degrees, which obviously just can't happen. It put the fans at full speed and it continued to read 259 degrees, even though the northbridge was very cool to the touch due to the fans running at full speed.

My guess would be you have a temperature sensor gone bad and the system thinks it is overheating.

Can you tell which fans are going at full speed? That's another thing iStat Menus can help you determine, how fast the fans really are running.
Click to expand...
Mine were running at 2700 with 1-3% power being used on all cores. It is an issue with the MP that I would bet money cannot be fixed. The fix is a new machine.

I wonder what causes it though because if the newer machines are affected by it there has to be something failing.
 
Ok, here are some details - would appreciate further feedback:

I installed istat menus.

With nothing running but safari (one window open) CPU usage is essentially zero:

# w
8:52 up 19 mins, 2 users, load averages: 0.09 0.10 0.04
#

However, istat menus shows fan speeds of:

Boost A: 5196 RPM
Boost B: 5205 RPM
Exhaust: 2799 RPM
Intake: 2804 RPM

(and so on)

And temps of:

CPU A: 25
CPU B: 25
Ambient: 24

(all temps between 24 and 30 C)


So ... it would seem the temp sensors are getting reasonable temps, and that those temps are low (77 degrees F and so on).

So if the system is getting good (low) temps, why are the fans running full blast ?

I can understand if the sensors were blown and they were reading wacko temps, but I don't understand this at all.

Thanks.
 
Follow-up:

I see what is happening now that I am watching the istat menus.

Things are normal ... then, at some random time, the temp for CPU A starts rising fast up to 100+ degrees C.

As would be expected, the fans ramp up to meet this temp.

However, this temp is erroneous, and after a few minutes it magically drops right back to 25-29 C, to match CPU B. So the erroneous temp readings go away fairly quickly.

BUT the fans never slow down. Even though all temps are back to normal, the fans remain at full blast.

So it would appear that either:

a) I have two problems - bad temp sensor AND faulty fan logic that never tells the fans to slow down

b) 2009 mac pros in general have bad fan logic and never slow down once ramped up to full speed.

Either way, I have now doubled the price of this machine. It was $3000 (or so) and I have now spent 6+ hours dealing with this issue. It is now a $6000 machine.

Now I will talk to apple about re-shipping or driving to the apple store, etc., and we can see about turning it into a $7000-$9000 machine.

Whee!
 
gjarold said:
Follow-up:

I see what is happening now that I am watching the istat menus.

Things are normal ... then, at some random time, the temp for CPU A starts rising fast up to 100+ degrees C.

As would be expected, the fans ramp up to meet this temp.

However, this temp is erroneous, and after a few minutes it magically drops right back to 25-29 C, to match CPU B. So the erroneous temp readings go away fairly quickly.

BUT the fans never slow down. Even though all temps are back to normal, the fans remain at full blast.

So it would appear that either:

a) I have two problems - bad temp sensor AND faulty fan logic that never tells the fans to slow down

b) 2009 mac pros in general have bad fan logic and never slow down once ramped up to full speed.

Either way, I have now doubled the price of this machine. It was $3000 (or so) and I have now spent 6+ hours dealing with this issue. It is now a $6000 machine.

Now I will talk to apple about re-shipping or driving to the apple store, etc., and we can see about turning it into a $7000-$9000 machine.

Whee!
Click to expand...

Your time is worth $500 per hour? I work with quite a few PHDs that make a lot less.
 
dr. shdw said:
This and a SMC reset will probably fix it.
Click to expand...


Ok, I reset SMC (white little button near front of case just in front of the first drive) rebooted a few times to see if that did it.

It did not, so I also did the cmd-opt-P-R.

Problem has not returned ... although there have been some boot cycles where it never manifested, so we'll see.

CPUA is 35-38
CPUB is 30-31

Is that typical for CPUA to always run a bit warmer on a near-zero workload ?

Thanks.
 
gjarold said:
Ok, I reset SMC (white little button near front of case just in front of the first drive) rebooted a few times to see if that did it.

It did not, so I also did the cmd-opt-P-R.

Problem has not returned ... although there have been some boot cycles where it never manifested, so we'll see.

CPUA is 35-38
CPUB is 30-31

Is that typical for CPUA to always run a bit warmer on a near-zero workload ?

Thanks.
Click to expand...

Probably since one is farther away from the fan and doesn't get fresh fresh air.
 
Personally, I would have just taken it back for a new one from the beginning. This is in no way normal behavior. I would rather get it replaced than to try to troubleshoot it, wondering if the problem could return.
 
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