Chosen Solution
Hey guys, I’m baffled with this upgrade I did last week. Upgraded my iMac 27in mid-2010 from i5 to i7 and also replaced original HD with a 2.5in 1TB HD (already installed a 500GB SSD as startup disk prior). I now experience some strange speed problems, when the fan kicks in my mouse freeze for a few seconds and then as the fans slow down I can move my mouse again, this happens very often since the upgrade and its like an advance warning when the fans turn on I expect to have my mouse frozen. Not only that but the mac itself seems to have this slowness everywhere, loading apps or running them. All the upgrades were followed using iFixit guides. 3 reasons I can think of: CPU (tripled checked I bought the correct one, wouldn’t work otherwise)Thermal paste Artic MX-4 (could this cause this much problems?)Removal of the original HD which had temperature sensor that kept the fans normal, I now use SSD fan control. Please help, not sure what I did wrong here, it’s driving me mad. Regards. Update (12/14/2020) Update on this issue. I took @danj ‘s advice and separate the two drives apart, start-up SSD stayed where the original drive was and attached to the heat sensor (this was the reason for the loud fans turning on and off). Second drive moved to where optical drive was and as a test I unplugged the optical drive sensor and that drove the fan mad, plugged it back in and attached to the second drive for heat sensor and now everything works perfectly. So keep those sensor plugged in and attached to the correct places.
Well, the good news is you did get the correct CPU. At this point we need to see if the onboard diagnostics runs. I’m suspecting it will not pass an error. If that happens we’ll need to look deeper using this great app TG Pro it will allow you to see clearly what’s happening with the thermal sensors and fans’s. We also need to look at Activity Monitor to see if kernel_task is running hard. It’s possible the CPU you put in is defective as you likely got a used unit. Inaddition over doing the thermal paste could also effect things as the paste needs to stay on the metal heat spreader not onto the base as the small SMT devices can be effected by the paste conductivity or its capacitance. Update (11/09/2020) This series needs a physical thermal sensor! You can’t cheat. Please install the sensor OWC In-line Digital Thermal Sensor for iMac Late 2009 - Mid 2010 Hard Drive Upgrade You really can’t over-ride SMC via software to replace the missing sensor. These software solutions only go so far. The best way to think this is you are playing poker with someone which the deck has four aces, you have two more aces up your sleeve so what happens when the other player places their cards down and they have two aces and one of the aces you put down you took out of your sleeve is the same ace! Who won?? Basically, the missing sensor is seen before the software loads to over-ride it so SMC latches in a failed state which the software over-ride can’t over come.
