Were you using HDMI audio when you got the panic? Based on the backtrace, I think it's possible you can add back WEG for 144hz and avoid the panic by not using the HDMI audio device.
I use WEG with my Radeon VII, but I can only think of a couple times I ever used the HDMI audio out.
You can reuse your RAM if you go to a Z97 motherboard with DDR3. You can buy a Haswell refresh processor for that. Look for refurbished, or new old stock sales, and it will be quite cheap.
If you're not reusing RAM, then you're in the same boat as anyone here who's building a new system.
In my experience, it can be caused by enabling the Above 4G decoding option. This option is sometimes needed, so it's very annoying if you have to CMOS reset and then reload a preset in order to change anything.
I think somebody on X299 said it was something else, for them, though.
Usually the extension is done with coax cable for the antenna.
However, there are also some wifi to Ethernet bridge devices you can get. I use one on a printer I have that's Ethernet only. If you can find one that's rated for the speeds you need, then I think that would also work fine.
This FTW K motherboard reminds me of the Asrock X299 Steel Legend. It appears that they updated it for the 32 GB DIMM support, but didn't reroute the PCI-e. It might mean that it will be one of the few refreshed X299 boards that is working for OS X!
@CHENM1NG, let us know if you get it booting.
There can occasionally be issues with bus frequency detection in Clover. So there's an option to override it.
To get the current value you run the command: sysctl hw.busfrequency
The sysctl output is in mhz and the Clover option is specified in khz.
I think the main difficulty is usually an MSR lock. Not insurmountable, though. Perhaps the X11SRM would be a good choice.
C621 is close enough to X299 to use KPG's guide, I think. And any Xeon W is probably a better choice than the other LGA3647 options (i.e., avoid Skylake-SP).
OS X doesn't mind it?
x8 usually doesn't affect much, most commonly only games that load texture data at a very high rate. x4 is more of a handicap, I'd say, but if you just need a display adapter it's alright. x1 for the GPU would be quite strange, IMO.
You should use Z390, and your client should use X299, which has either 44 or 48 lanes (although 48-lane boards are not hackintosh compatible).
(Personally, I would get a Z370 board. They're less hassle for hackintoshing.)
For your 2 NVMe drives, I like this adapter card - get 2 of them...
While I agree that dealing with the bifurcation stuff doesn't make sense on a Z390 board, OP asked about RAID. You can't do it with the PCH slots, because there's not enough bandwidth in the DMI link.
I tried it once, and it gave no performance improvement.
Yes, as long as your motherboard can do the bifurcation.
But it's an x16 device. You don't have enough PCI-e lanes to take advantage of it, unless you use IGPU only. That's why I recommend the dual card that's x8, or more simply, just use 2 slots.
You can also look at the OWC 4m2 card.
Now that you've gotten past the APFS error, I think your problem is USB related. Maybe try adjusting the XHCI handoff setting in BIOS?
@donw35's advice to use updated kext versions is important, also.
Yes! Try not to use any file until you know what it does, and that it's solving some problem...