iM 4,1-14,4 Ambient/LCD Proximity/Optical Drive temperatures erroneous, what is the common cause? (SOLVED?)

[piwikiwi]

Hi there, I recently opened up my 2010 iMac 11.2 and installed a "Metal" GPU.

Everything seemed to have gone very well, although I had some Fan issues that I "corrected" using Macs Fan Control.

Upon closer inspection it appears that the "Ambient", "LCD proximity" and "Optical Drive" values are erroneously low, often 0 or 1 degrees Celsius although the "Ambient" does eventually rise from 0 to about 20 C. The values were correct prior to taking the machine apart.


Edit: iStat reveals that my 3.06Ghz dualcore CPU is restricted to 1.2Ghz right now too.


Google tells me HDD temp connections (I am using an SSD), sensor cable connections, slightly damaged board solders and similar are suspects.
I will open up the machine but it would be nice to know if the symptoms match one particular scenario to narrow down the effort.

Does anyone have the diagnosis for the symptoms?

Thank you very much,

Paul

 

[piwikiwi]

Hello,
So I’ve loosened and reinserted the plugs for the LCD Proximity and Optical Drive sensors. Everything looks okay.

Unfortunately the Ambient/LCD Proximity/Optical Drive sensors still show incorrect values (LCD and Optical Drive typically show 0 or 1 degrees celcius).

Macs Fan Control will control the fans perfectly (without MFC the fans spin at full speed), but the most pressing problem is that the CPU is severely throttled when sensors are impaired.

Does anyone recognize this situation and know what the common failure might be? Or possibly a workaround to unthrottle the CPU?

Thanks,
Paul

 

[piwikiwi]

Update:

I have selected the "Disable Firmware Throttling" option in OCLP in an attempt to unthrottle the CPU.

While I can't be sure (because now iStat won't display certain parameters) it does appear to allow the CPU to work harder because CPU temperatures have gone up when I tax the machine.

If anyone has thoughts on this, please share.

Thanks,
Paul

 

[piwikiwi]

Update:

It looks like the AMD Firepro GPU may be the “common cause” of the sensor errors:

Post in thread '2011 iMac Graphics Card Upgrade'
https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/post-33804686

Anyway, I am happy that the issue doesn’t appear to be the result of me damaging the machine and that using OCLP “Disable Firmware Throttling” and Macs Fan Control restore good functionality to my vintage iMac.

Hopefully someone else might find this info useful someday.

Thanks 👋