iMac CPU Fan 0 RPM after SSD upgrade?

Hi there.

I followed this guide: Installing iMac Intel 27" EMC 2390 Dual HDD or SSD Drive - And purchased the iMac Intel 27" (Mid 2010) Dual Hard Drive Kit kit to help me during the operation.

To install two 512 GB SSD drives. I replaced both the internal 1TB Seagate drive + installed a second SSD behind my optical drive.

The operation went fine. I made a loop cable for the thermal sensor on the harddrive. Both SSD's are woring perfectly, and so is the Optical drive.

But when starting up I can hear the harddrive fan go nuts, but at the same time iStats shows that the CPU fan is 0 RPM. I have checked the connector, and it's well fitted, so I haven't forgotten it. The Harddisk sensor is reporting very low temp. due to the loop cable.

Before I send it to repair. Is there anything I should be aware of. I have googled and found that some had problems with the mainboard afterwards. But just want to make sure, that I haven't missed the obvious.

I haven't had the mainboard out, Are there any connectors on the other side of the mainboard, that could play an role?