In the past few months, I ran into a kind of problem that I have never experienced in all these years experimenting with Hackintosh.
I set up Sierra 10.12.6 on a machine with this configuration:
Motherboard: ASUS H87M-E
GPU: Intel HD Graphics 4600 (GT2)
I used Clover 4114 as bootloader. To make the internal graphics work, I inject changes in DSDT tables from GFX0 to IGPU at boot time. Inject Intel is also enabled with ig-platform-id = 0x0a260006. Two kexts are used for audio and LAN. My config.plist file is attached.
Most of the times, everything works perfectly. Full QE/CI support, full resolution, no evident issues. Sometimes, the system does not boot at all. The boot hangs at "waiting for IGPU" and it seems that does not recognize the graphics card (no "PPGTT is enabled", for example, when the system does not boot). Even crazier, after one or two reboots without changing anything in the config.plist, the system starts again and everything works again, out of the blue.
I suspected this behavior was due to some weird BIOS setting, but I already fixed the amount of GPU shared memory and this did not solve the issue. Do you have any idea of what might be the cause? The fact that the issue is not permanent or even deliberately reproducible is making me go crazy.
Thanks for your help,