I'm keen on this idea, ....... go back to El Capitan from High Sierra, and permanently disable the Radeon GPU.According con Realmacmods:
"The safe boot clears OS level GPU preferences, that may interfere with the following process.
This will now cause your MacBook Pro to stop switching to the Radeon automatically, but it will still draw power, create heat, and be visible to the OS.
We discovered that simply removing 1 resistor will resolve this.
The resistor in question is R8911 on the 17″ MBP and R8911 on the 15″ MBP
a 1 Ohm resistor that provides a current path to the ISL6263C DC to DC Converter.
Just remove it. The preferred method is a professional reflow station, but an iron and a steady hand will get you where you need to be. If you used flux to remove it (not needed), make sure you clean up with a little Alcohol or other suitable solvent.
That is basically it. Next time you boot up you will notice your GPU defect issue is gone, and you will no longer see the AMD GPU as installed hardware.
A small warning: It has been tested that this mod will survive a SMC reset as well as Battery Removal. It is not yet known if it will survive a NVRAM reset. For this (and other security related) reasons, it is recommended that you set an EFI Password. This will make it impossible to accidentally reset your NVRAM. Just don’t ever forget this password. Seriously, don’t. Ever.
In the event that a NVRAM reset removes the EFI mod, replacing R8911, or even bridging the pads for R8911 will restore functionality so you can reapply the EFI mod. Really though, lets just stay away from the NVRAM resets. They rarely fix anything that couldn’t be fixed otherwise anymore.
ADDITIONAL STEP FOR HIGH SIERRA
High Sierra requires an additional hardware mod. This jumper wire is different between 15″ and 17″, both are shown below. Without this mod, your screen WILL NOT turn on after going to sleep. On the 15″ we just need to put a small jumper wire (enamel wire) between PIN 2 of R9704 and PIN 1 of C9711. Logic board does not need to be removed for this step. Only bottom cover removed.
I'm in El capitan, and I have not intentions to perform an OS upgrade, so, I don't need the second mod, I only did the first one.
I find the manual method of writing the code to achieve this a little daunting, and was wondering if anyone else had used Realmacmods Radeon disable utility downloadable for $10.