Slow fan speed changes with temperature changes

[oscgonzales]

On my 2006 iMac the program version 1.0.1 is very slow responding to temperature changes. When I run something that uses about 80% of the CPU the temperatures naturally go up but even when the temperature is above the sensor set-point (using the GPU sensor to change CPU fan), the fan doesn't speed up for a couple of minutes. Then when the temperature is down is doesn't slow down right away. Too much hysteresis! Is this a bug or is it intended?

[Steven]

Well, it can be true if temperature changes too fast this issue can take place

using the GPU sensor to change CPU fan

This is absolutely not correct

[Jon_K]

Is this behavior due to Macs Fan Control, or due to the Mac hardware or OS?

[Steven]

Jon_K, do you have the same problem? Fan speed is too high after temp sensor value dropped?

Please share your experience with some technical information (screenshots, example values).

[Jon_K]

I'm using a Mac Pro mid 2010 5,1. I have Boost A, Boost B & Intake all set at heatsink 50C/75C. Ambient is 37C. CPU A is about 54C at idle. In this state Boost A is at 800, B at 800, Intake at 600 & Exhaust at 950. When I put full load on the processors, the temps quickly rise. The fans don't spin up until CPU A is about 87C - 1 min 50 sec after full load was applied. Once the fans spin up, CPU A drops to 72-73C. After about 4 minutes, the fans spin down. CPU A then rises to 82-83C and holds. In this state Boost A is at 1700, B at 1500, Intake at 1150 & Exhaust at 1430.

[Steven]

Ok, this is clear, thanks. The sensor-based algorithms will be improved in the next version

[Jon_K]

Behavior did not change with 1.1.1

[Steven]

Yes, but it will be fixed in next updates

[Steven]

Improved in 1.1.5

[Jon_K]

1.1.5 is much better. Now the fans don't play catch-up, sounding like jet engines. The temps rise, and the fans spin up with them. Temps never get as high as before.
Thanks!

[Steven]

Great!