Late 2012 21" beyond slow/cannot install macOS

[tdubbed]

No luck Fish.

Actually, I disassembled the entire thing, removed the CPU/GPU cooler, reapplies thermal paste, reassemble...

No dice. DEMORALIZING.

Next may be a professional repair shop.

 

[Fried Chicken]

Install on an SSD; reapplying thermal paste wasn’t necessary unless u had excessive temps (and by excessive I mean 95°C or higher)

 

[tdubbed]

Install on an SSD; reapplying thermal paste wasn’t necessary unless u had excessive temps (and by excessive I mean 95°C or higher)

Oh, I understand this, but I've tried everything else. I'm throwing spaghetti at the wall here.

I cannot explain why kernel_task is destroying usability.

 

[DeltaMac]

High kernel_task, at least for me, is often fixed by an NVRAM reset, common after a fresh install of macOS.
The fix I usually use for that is another reinstall - just a simple reinstall of the system, followed by an NVRAM reset, holding for at least two chimes.

 

[tdubbed]

Thanks Fish.

The amount of NVRAM resets I’ve done is obscene.

Time to close the thread. Thanks for your help everyone. This “free” computer may turn into a $350 money pit (logic board)?

Not sure it’s worth that.

 

[Fried Chicken]

Thanks Fish.

The amount of NVRAM resets I’ve done is obscene.

Time to close the thread. Thanks for your help everyone. This “free” computer may turn into a $350 money pit (logic board)?

Not sure it’s worth that.

Might be the case of a bad logic board. Did you try a hardware test?