F22 BIOS is out for your mainboard and I suggest you update your BIOS.
F5 BIOS doesn't have the feature for disabling the "IOAPCIEntries 24-119 Entries" which is necessary to run macOS, unless you edit the BIOS manually. There is another essential update which affected many Gigabyte mainboards and that's adding UEFI entries each time the computer reboots which is resolved and maybe that's why you couldn't get to UEFI BIOS settings.
So first of all Update the BIOS, then go to BIOS and "Load Optimized Defaults" then take a look here:
In BIOS from M.I.T. choose Advanced Memory Settings
I. From Extreme Memory Profile(X.M.P.) I Choose [Profile1] it's crucial to choose this option if you want your memory modules work with their full frequency.
II. Enter the correct System Memory Multiplier which in my case based on my 2666MHz DDR4 it must be 26.6.
III. Select [Enhanced Performance] from Memory Enhancement Settings. You can choose any of the options I chose Enhanced Performance.
IV. From BIOS Features Fast Boot is disabled, Windows 8/10 Features is set to Windows 8/10 WHQL, LAN PXE Boot Option is disabled, CMS Support is Enabled, Storage Boot Option Control is UEFI Only, Other PCI Device RPM Priority is UEFI Only and Network Stack is Disabled and Secure Boot State is Disabled.
V. From Peripherals: VT-d is disabled, Internal Graphics is set to Auto, Audio Controller is Enabled, Audio DSP is Disabled, PCH LAN Controller,SATA Configuration is set to AHCI, Wake on LAN and High Precision Timer are Enabled. I didn’t patch my BIOS because of a great job that Pike R Alpha did with a kext based patch for Skylake processors and to patch the AppleACPI.kext.
Under Super IO Configuration Serial Port must be disabled as well.
UPDATE: I recently updated my BIOS to f5h and IOAPCIEntries 24-119 Entries is there so if you are using that version of the BIOS or anything prior to original f4 you don't need to use the ACPI patch.
VI. Save your new settings and reboot.
for more info see: http://www.insanelym...ng-5/?p=2187772
Do you have access to any working Apple computer or another working Hackintosh?