Cannot boot Hackintosh with GTX 980 or 970?

panic(cpu 2 caller 0xffffff8000379458): "a freed zone element has been modified in zone kalloc.64: expected 0xdeadbeefdeadbeef but found 0xdeadbeef00000000, bits changed 0xdeadbeef, at offset 48 of 64 in element 0xffffff8037690d00,
Debugger called: <panic>
Backtrace (CPU 2), Frame : Return Address
... : ...
BSD process name corresponding to current thread: kextd

Simply going ahead and booting with the Maxwell-based Nvidia GPUs will likely cause problems. Whether it’s physically removing the graphics card, or switching to the integrated GPU in the BIOS, you need to temporarily disable it before the Nvidia Web Drivers are installed.

I. Disable discrete graphics

1. Enter your BIOS.
2. Make sure your on-board GPU is enabled.
3. Switch the video output to IGFX.
4. Save and exit.

II. Initial setup

1. Plug your video cable to the motherboard’s port instead of the graphics card.
2. Boot up Mac OS with the boot flag -v. If you are getting errors, try IGPEnabler=No, -f, -x, GraphicsEnabler=No, nvda_drv=0, nv_disable=1.
3. Once you’re in the system, install the Nvidia Web Drivers.
4. When asked to reboot the system, do what you did in step 5.
5. Go to System Preferences and enable the Nvidia Web Drivers.
6. Don’t reboot, shut down.

III. Switch back to discrete graphics

1. Go into your BIOS and switch the video output to PCIe0 or whatever PCIe slot you have your graphics card in.
2. Disable the integrated GPU.
3. Save and exit.
4. Plug your video cable back into your graphics card’s port.
5. As you boot Mac OS, trying using -v only.
6. You should now be able to use your Maxwell GPU on Mac OS X with full GPU acceleration.