MacPro fans full speed?

Hi. I'm new to mac pros and macs in general.
I opted to buy a used mac pro 2006, 2.0 quad.

The mac installed osx snow leopard fine and boots up fine. Except the fans go crazy as soon as it's switched on. And does not stop.

Only way to stop them is by turning the mac off or putting to sleep.

I have been told to run apple hardware test and it came back clear.
I was then told to use Istat to check the fan speeds.


Figures show approx:
Power suply 599rpm
Exhaust 1547rpm
CPU fan 499rpm
HD expansion 2865rpm


Iv checked that the HD is sitting right. Changed hard drive bays. Changes hard drives. Reset SMC. Reset pram.

Still no joy. Any other ideas?

I'm certainly no expert when it comes to a Mac Pro but it seems to me the only fan that's ramping up somewhat is the HD Expansion. The other fan speeds look normal to me.

However, like I said above.... I don't know too much about the Mac Pro but we have several folks and a staff member who own one and should respond with a better answer. So hang on for a bit.

Iv noticed that. I thought it might have been my HD not connecting to the heat sensor. So I got two western digital HDs to be sent to me from the original owner and they still didn't sort the problem.

I'm thinking maybe the heat sensor got unplugged somehow?
Or what Eles causes the HD fans to go crazy?

What you describe trademark is precisely what happens if a heat sensor has not been connected properly. The fan/s concerned simply power on at full speed. Open her up, remove the hard drives, and have a good look around. The sensors simply plug into the motherboard and you do not have to use a great deal of force to get a connection, but it is important the clips be lined up properly prior to applying pressure.

This may help:-


http://www.scribd.com/doc/51667130/41/Hard-Drive-Temperature-Sensor-Cable

harryb2448 said:

What you describe trademark is precisely what happens if a heat sensor has not been connected properly. The fan/s concerned simply power on at full speed. Open her up, remove the hard drives, and have a good look around. The sensors simply plug into the motherboard and you do not have to use a great deal of force to get a connection, but it is important the clips be lined up properly prior to applying pressure.

This may help:-


Hard Drive Temperature Sensor Cable

Click to expand...

Thanks for the reply.
If my heat sensor(s) are loose or broken I shouldn't be able to get a reading would i?
As it stands istat shows all the temperatures at about 28 degrees each.

Also now my CPU fan is high too. 1500rpms.

I have done the apple hardware test again. extended version.It came up with this code:



4SNS/1/40000000: TH3P



During the test im sure the machiene went quiet(er) for a few minutes.

Well we are getting somewhere, and looks like it is off to Apple Service Centre.

4SNS tells us it is a heat sensor fault, and TH3P is a hard drive heat sensor.

Its a used computer. There is no AppleCare. And they charge far too much.
Say a heat sensor was loose. Would that code still come up?

Yes and make the fans run at full steam also.

Now you know where to begin, remove the drives and check under them that all leads are connected to the mobo. They look like miniature graphic card connectors on the mono. See page 137 on the link number 4.

If there are any that are loose from the drives use double stick tape as that seems to be all that is used.

I never understood this, if there heat sensor is unattached why would the fan run full speed? It isn't detecting any heat.

I'm not an engineer nor do I play one on TV so take this with a grain of salt. I could be wrong.

If I were designing this type of system I would design the fans to kick into gear when no reading is obtained. It seems to me it would be better for the fans to kick in unnecessarily than to assume no reading means things rare OK and not kick in when perhaps they need to. Less chance of damaging the drive.