Mid 11 Temp sensor problem causing lag of performance

Now i have searched the web a few months about my graphic performance problem on my 3,1ghz 2011 iMac.. The 6970 1gb card has absolute no power in OSX.. but works perfect in windows..

I have a fan speed problem caused by the ambient temperature sensor which is not present in the list of sensors in all temp sensor programs..
I understand that this missing temp information is causing the SMC to tell OSX to slow everything down.. Fair enough.. Everything works in windows so i guess windows doesn't get the info to slow down .. But i hate windows..

I have tried change the ambient temp sensor.. but still no success.. If i reset the SMC the ambient temp comes up with 128c reading.. i guess that is a "faulty mode" value..

Every thing points at the logic board.. Witch is very expensive.. (buy another iMac 2. hand instead!!) Yeah.. But I'm a fighter.. Everything else on the computer works fine..

Would it be possible somehow to cheat the SMC -> OSX info transfer of temp values.. or faulty mode.. ?

And can someone confirm my problem by trying to disconnect the ambient temp sensor and describe their iMacs behavior ?

I keep my fans down with "macs Fan Control".. works perfectly.. If i close the program, CPU and Optical fan run max speed.

But i have still no graphic performance.. (games runs very bad even in very low settings) and iTunes album scrolling is crappy

Any ideas?

/Kristian, Denmark

 

Hey there.. Yeah decreased fps.. feels like old games them I turn off gfx acceleration and use software acceleration..

But no i didnt find a solution.. I bought a 250gb sad and installed win 7 on half of it.. and play diablo and borderlands2 from windows.. and i must say windows runs VERY smooth on a mac..

To get rid of the fan noise i use Macs Fan Control.. works both in windows and OSx.. And works fine adjusting the fan speed in games.

Its possible to buy a used main board from TheBookYard.. but still expensive.. I guess the only solution is to replies the main board / logic board.

Let me hear if you find a solution.. Next time I just replaces the 1tb hard drive with a ssd.. i never use 1tb anyway.. Then i don't harm the main board..

 

The solution has been found!!! I just made the fix.. and it works..

The solution can be found here.. With some soldering skills you can fix your macs

https://www.ifixit.com/Answers/View...+sensors+or+fans+after+Dual+Drive+Kit+Upgrade