Fan issue after changing Video card - Late 2009 iMac

I recently changed my Video card and now my CPU fan is running full speed. I am running HW monitor to troubleshoot and I see CPU core 1 temp of 129Deg C and CPU proximity at 129Deg C. Everything else looks normal.

Does anyone know what this means or any idea how to troubleshoot this ?

Have you tried resetting the SMC?

https://support.apple.com/en-us/HT201295

I did multiple times. Nothing I'm afraid. Its very strange as when I look at the HW monitor values it look like the CPU proximity sensor and CPU Core 1 temps are not getting feedback.

Did you by chance disconnect the hard drive and overlook the heat sensor cable and connector?


https://eshop.macsales.com/item/OWC/DIDIMACHDD09/

You read my reply to the other OP in another thread. Make sure you have the video cable connected correctly from the display to the logic board and that you did not damage the video connector on the logic board. As I explained to the other OP, that's a common problem with iMacs especially older ones like yours. If that connector is damaged or if you attached the cable backwards, the fans in your iMac will run full RPM. And since you changed the video card, that's a likely suspect.