I see this thread has been going for some time and it is the best one I found on the Internet so far. I purchased a new SSD drive for my late 2009 27" iMac and before I dismantle everything, I would like to be prepared for all operations in advance. This includes replacing the HDD by a SSD but also deal with the Thermal sensor issue. I find Alexandre's answer to use a 2N3904 transistor simple and interesting and would like to know a little more about it, so please allow me to ask a few questions: 1. Has this solution been tested and validated by anyone? 2. If so, does this setup provide a temperature reading when using a tool such as MacsFanControl or iStat Pro? 3. Does the reported temperature (and variation) make sense? 4. Does this solution allow HDD Fan to behave normally - without any additional software control (ie. not spin at max speed at startup and increase speed reasonably if temperature goes up)? If this solution has not proven to work, I will most certainly just jump the connector, but will...