Problems with SMC after cleaning my iMac

I didnt pay any money since they were unable to fix it. Question I have now, could there be done something to fix existing logic board?

@yuriisuhov - Do you have a DVM? Do you know how to read a schematic?

You'll need to get the schematics and boardview drawings so you can trace out the different sensors. Clearly a sensor is not communicating to your logic board. I wouldn't assume the logic board was the failure here more likely something else.

Hi Dan! I ordered a new exact same logic board, before I proceed though, I have couple of technical questions if you don't mind:

- Im planning to remove existing hard drive and leave blade SSD in (I had fusion drive), should I remove HDD cable completely from internals? Will that make fans spin to max?

- What kind of thermal paste should I apply to GPU processors? Is it OK if I apply same thermal paste everywhere?

- Is it possible to damage board by over tightening spring loaded CPU holder? I heard that iMac boards are very fragile when it comes to tightening screws.

Thats about it, hope you can give me some advice!

Thank you!

● Fusion Drives use a small SSD's for the cache drive. Your system would be very lame without having the needed space to do much other than boot up. I would either upgrade it to at least 128 GB (still on the small side). I would instead take it out and then just put in a SATA SSD drive (512 GB)

● Thermal paste is no different between the CPU and GPU chips. But! You need a special gapping paste (viscous) or thermal pads for the Video RAM chips (see pic above)

● Yes! You can damage things if you don't do it correctly. Think how you mount your cars tires rim. You tighten one nut (top) just enough to grab the threads, then you go across and do the apposing side then you jump back over my one on the top and then back to the bottom jumping over in same direction until all of the nuts are threaded and then you work them in slowly in the same manor! You use this same approach here. I use a torque screw driver to make sure I set all the screws correctly (not over tightening or leaving them loose).

Thanks Dan!

My SSD blade is 128GB, since it was 3TB Fusion Drive. My plan was to remove internal HDD with its wiring and just connect external 1TB SSD, in that way I will be able to take it with me ( this is family computer, which has MS WORD and movies on it).

So I assume I can just remove hard drive with its wire and not worry about any confusion on logic board?

Thank you for your help!