Specifications (I am just listing critical components):
OS: MacOS High Sierra 10.13.6
Intel i7-8086k (or i7-8700k)
64GB DDR4 3200 RAM - G.Skill Trident Z
Gigabyte Z370 Gaming 5 Motherboard
2x GTX 1080Ti
1TB Samsung 960 Pro NVME SSD
EFI.zip: https://www.dropbox.com/s/yazadrzjx3k5ghx/EFI.zip?dl=1
In order to install, follow this Youtube guide. I am using APFS file system, not HFS+: https://www.youtube.com/watch?v=8jKtfMWinvo
When you have a bootable USB drive, copy all files from my EFI/CLOVER/kexts/Other/* to the bootable drive's EFI/CLOVER/kexts/Other/*
Do not copy the full EFI folder on your bootable install USB stick. Just install the OS first (make sure you're using iGFX video output in BIOS). Once the system is up, copy and replace the whole EFI folder. Initially, the system is going to be using iGPU. Install nVidia drivers using this guide, but most of the items are already done for you in my EFI.zip. Still follow this line by line: https://hackintosher.com/guides/properly-install-nvidia-driv...
Use CloverConfigurator to setup a new Serial number in SMBIOS section for iMessage, etc.
BIOS settings on the Gigabyte: https://hackintosher.com/builds/gigabyte-z370-aorus-gaming-7...
You can OC after everything is working well. Sleep, USB3.2 ports, USB-C port, wifi, audio, ethernet, all PCIE devices, both GPUs, etc! Everything is working!
Dual Monitors: I have 2x 4k monitors, one hooked up to the motherboard Display Port and the other hooked up to the 1080Ti in the 1st PCIe slot. If I only want to use nVidia cards, then I hook both monitors to the 1080Ti in the first slot. Splitting both monitors on each 1080Ti is glitchy. Either connect both to the same DGPU or connect one to iGPU and the other to a DGPU.
I removed the Gigabyte wifi/bluetooth module on the motherboard and replaced it with the Broadcom BCM94360CD chipset you can buy on eBay ($69) for handoff, airdrop, etc. Stick it in an empty 4x PCIe slot.
Conclusion: It is a pain in the ass to get it working, but if you use my EFI.zip, I have installed this thing on another PC just today. I have liquid cooled all components including both GPUs - I can't believe this is a thing!. I also run linux and Windows triple boot in Clover Bootloader. It is so beautiful.
Once it works, buy a copy of CarbonCopyCloner (CCC) and clone your main OS on another drive. This way, if a future update fucks up your installation, there is always a bootable backup. When you make a CCC backup, make sure to manually copy EFI folder into it. Test if your backup works as a bootable drive (it should be verbatim copy, just need to sign into your iCloud again).
Enjoy!