iMac fan spinning after graphics card swap

[Big Jim]

iMac 2010 i3 4gb ram, HDD
Issue couldn't see much of the screen due to graphics artifacts.

Replaced the GPU like for like with a used one.
New card works fine, but now the CPU fan spins at full speed after a couple of minutes.

Using a temperature monitoring program all temps look well within limits, and we are able to slow fan down either manually or by telling the program to link the fan speed to the CPU temp.

Apple hardware test throws up an error
aht 4sns/1/c00000008: ts2p- - 124

a little bit of digging leads me to believe that 4SNS means a sensor fault and the "c" denotes its a cpu sensor, however all of those sensors are correctly reporting temperatures, unless a faulty sensor doesn't show in the software at all, which sensors should I be seeing if that is the case ?

 

[phaZed]

It could be a failing sensor, just not failed.. the iMac is going to 'poll' that sensor every so often... much of what could be reported correctly, but then it could fault during one of the pollings and the iMac goes into full blast mode. Just a guess.

 

[overburnz]

Is everything plugged in correctly? Did you plug the graphics card sensor on the back of the logic board? Is an SSD the main system disc?

 

[thecomputerguy]

You might have a bigger problem on your hands but I've used this before when I upgrade an iMac to an SSD and the HD loses it's temp sensor so the iMac fan spins at full blast all the time. Use at your own risk.

ssdfanctrl

exirion.net

 

[Big Jim]

As far as I know everything is plugged in correctly, all temps seem to be reported correctly when we use software to check them.
It still has its original HDD in, we have had to use fan control software in the past for customers when upgrading to an SSD for them.

Its looking like that is going to be the solution for this one as well, but every now and then I like to try and get to the very bottom of a problem as a learning exercise.

 

[overburnz]

As far as I know everything is plugged in correctly, all temps seem to be reported correctly when we use software to check them.
It still has its original HDD in, we have had to use fan control software in the past for customers when upgrading to an SSD for them.

Its looking like that is going to be the solution for this one as well, but every now and then I like to try and get to the very bottom of a problem as a learning exercise.

yes if you have a SSD the fans will spin even if you have the original HD