I happen to have a first-gen unibody MBP (Late2008), equipped with Nvidia 9400M + 9600M GT gpu's. Used it until about a year ago, when the discrete 9600M gave up and machine always kernel panicked in boot.
Now I'm trying to revive the machine. I booted the machine from old HDD with 10.7 Lion installed to it. To my surprise it booted fine to desktop and everything seems to work normally. Only that when I try to switch to 9600M, nothing happens, and the machine starts to run really hot even when idle. But again, using only integrated graphics seems to work ok.
I'm fine with the machine only working with the integrated graphics, but the problem is that post-Lion systems won't boot, to me it seems that they try to access the discrete GPU and panic when it fails (always nvidia mentioned at crash dump). So, my question is, is there any way to "disable" the 9600M GPU, so that the operating system would only see and use the integrated one? Or maybe just delete all references to 9600M from for example Yosemite's graphic drivers (and how it would be done)? Of course if this is not possible, I just have to stick with Lion, thats better than completely dead machine.
If anyone has ideas, please share