Prohibited sign at boot from HDD (Skylake)

[prophan]

For a GTX 970, your config.plist should have inject nvidia = false (like in the last one you posted).

If you edited the config.plist on the system drive and now it won't boot, try booting with your old USB drive (use your BIOS hotkey to select a boot device to be sure) and restoring the config.plist on your system drive to what it was before.

You might try with inject intel = true and then with your onboard graphics enabled in BIOS and with onboard graphics disabled in BIOS just to see if one of those configurations comes out better. You can also make sure you have the latest Nvidia Web driver installed.

You only have one graphics card, right? And your monitor is connected on a digital port (not VGA)?

Sorry for bumping, but I can't solve this problem. Search the forum for answers, but doesn't seem like this is an issue for many people.

My last post:

My config.plist has inject nvidia = false. The computer won't boot with the nvda_drv=1 boot flag, but works just fine with nv_disable=1. Tried several times now. Re-installed the Web driver for the right OS X build.

The monitor is connected via the HDMI port.