MacBook broken GPU workarounds

[Riccardo Mottola]

Hi all!

A macports off-topic question, but since you are of course Mac users, 
maybe you can share your experience and help.

My MacBook with discrete AMD GPU had a failure on it, a quite common 
problem apparently. I did not stress it with gaming, heavy 3d or 4K 
videos...

The best solution would be of course to have it "fixed" by replacing the 
GPU or by doing a proper reballing of it, but that is expensive and 
nobody does it really. Most often just re-flowing it is attempted - even 
if advertising it differently. Professionally or with home tricks, but 
often this either does not work (the simplest being to try to cook 
itself by removing the fan and keeping it on) or fixes it for a short 
period of time, since the lead-free solder is crap anyway!

Next best is to somehow disable the discrete GPU, since the intel one is 
more than enough for casual use, but a proper way to disable the 
discrete one is needed. There are a lot of tricks around, but none 
complete or good enough that it is permanent. My GPU is fried enough 
that beyond displayng garbage, it may lock up the boot process - so 
small apps do not help.

I run a small utility program which reprogrammed the EFI/BIOS/OF 
whatever and then moved away all kernel modules. This yielded a decently 
usable computer again, but with two big related issues

- after sleep wakeup the video remains black

- screen brightness is not settable


The problem is known, but none of the tricks I found on the web is 
working. I see repairers "selling" a solution which promises a way of 
disabling the discrete GPU without the mentioned issues, so it probably 
exists.


Anyone can share his experience and tricks?


Thanks, Riccardo