So here is my situation and story. I have a late 2010 iMac 27" i5, I decided to buy the 128gb M4 Crucial SSD to install as a secondary drive. I bought the whole harness and wiring kit off Ebay for it with the SATA cable, replacement power cable and the plastic holder for the SSD. So I used this tutorial http://www.twam.info/hardware/apple/installing-additional-ssd-in-mid-2010-27-imac#comment-3102 for helping in installing it. I did remove about everything (power,LCD backlight board,superdrive,airport, and the logic board. After taking it apart about 6-7 times and realizing I needed to put the power in first to the 1TB then the SSD, the drives showed up. In the middle of all of this, I accidentally pulled the LCD off the case without realizing the LCD Backlight sync cable was still plugged in. I almost ripped off the connector the board. So I tried to re-tape the connector in and prayed it would work, luckily the display is still fine. I actually ordered a replacement board, just in case to make sure it won't fail on me. So after the whole install and now knowing the iMac interior like the back of my hand, my CPU fan is going crazy at 100% and showing 0rpm on my OS when i install any fan reading software. I double checked the CPU fan (lower left of the front of the iMac) cable to make sure there wasn't any loose cables from the 4 that connect in the connector, I checked every cable to make sure they are plugged in. I've read numerous installs on forums around the internet and some people have this issue after install an additional SSD, but no answers as to why its happening. I don't know who to go to for support so I'm hoping someone on here can give me some ideas. BTW the SSD is blazing fast! I have all my applications and OS on the SSD and home folder on the 1TB, still crazy fast for PS and anything else I throw at it. Update: I've tried using SMCFanControl to see if I can modify the fan speeds, HDD and ODD look fine (900-1500rpms) and CPU showing 0rpm. I'm thinking my SMC is shot! (I've tried PRAM and SMC reset but to no avail) I also tried putting everything back to factory (cables and all) and the CPU still ran at full speed telling me something went wrong.