Hello, I performed the Dual Hard Drive Kit upgrade as suggested in the guide at http://www.ifixit.com/Guide/Installing+iMac+Intel+27-Inch+EMC+2429+Dual+Hard+Drive+Kit/7575 I followed the steps precisely during the whole process. After the second drive (SSD) was installed, I booted up the iMac and heard loud fan noise after a few seconds. Both CPU and ODD fans are running at full speed. I have tried resetting SMC/PRAM, but to no avail. I reassembled the logic board twice, with and without the Dual Drive Kit upgrade. It still didn't fix the problem. I have also noticed that it is not just the fans that are loud, my game which I play every day at 30fps, is crawling at 6-7fps after the upgrade (still utilizing the HDD though, not the SSD). Running the Apple Hardware Test revealed failure with TA0P code, which indicates Ambient Temperature sensor/connector failure according to some google search results. Moreover, Temperature Gauge Pro app reports the following: Some further Googling has revealed that this person had a similar problem and flipping the LCD Thermal Sensor Cable fixed it for him: http://forums.macrumors.com/showpost.php?p=16423197&postcount=13 However, I removed the LCD panel from the iMac and booted it with external Cinema Display. The fans are still loud. So I doubt that the problem is with LCD sensor for me. Maybe I should pay attention to the Ambient Sensor/connector, since the AHT failure also reported a fault with that. Another thread mentions a similar problem, but doesn't include any solution: http://forums.macrumors.com/showthread.php?t=1669643 Any help would be appreciated on how to approach at fixing this Ambient Temperature Sensor/connector. I can approach a hardware technician if the fix demands it. TLDR: * After installing 2nd drive (SSD) on 2011 27'' iMac, * CPU and ODD fans are running at full speed, HDD fan at normal. * Degraded gaming performance at 6-7fps. * Failure in Apple Hardware Test with code TA0P (ambient temperature sensor). Thanks!