Done, thanks. I guess both are somehow correct (the layout I mentioned before was used in eary Polaris reference cards, I think), but mentioning the layout used/supported by Apple is better, I guess.
I've been a bit out of the loop, so: Can someone comment on Vega? Which framebuffer is usually...
I know I'm late, but I just updated my old GA-P55M-UD2 build, which was rock-stable running El Capitan before, to High Sierra and encountered two major problems. Since this board was quite popular at its time and no one mentioned those problems with this board I'm wondering whether...
Did you check wether the 290's device ID is in the drivers in Mojave? Can't check myselt at the moment, can't update yet due to missing WebDrivers.
If it's missing, try spoofing it to 290X's ID. Or try using Lilu/Whatevergreen with vanilla Clover settings.
Years too late, but I don't like posts without solution, so:
My Asus Z170M-based rig started to show the same symptoms (same wake reason, same problem in Win10 dual boot install). I fixed it by restoring BIOS settings and starting from the scratch with minimal changes (those needed to get macOS...
The Type-C port on your mainboard is data-only, there's no way to use it for transferring video signals. It's still possible to drive it using DisplayLink technology (like you did), but it's quite slow on macOS.
In theory you might be able to attach it to a DisplayPort with an DP to USB-C...
The lag is most likely caused by the WebDrivers, not by your new display. Read up here: https://www.tonymacx86.com/threads/nvidia-releases-alternate-graphics-drivers-for-macos-high-sierra-10-13-3-387-10-10-10-25.243857/
It's a bug caused by the most recent WebDriver build, details are in this thread: https://www.tonymacx86.com/threads/nvidia-releases-alternate-graphics-drivers-for-macos-high-sierra-10-13-3-387-10-10-10-25.243857/
The older driver has to be modified, otherwise it won't load on 10.13.3. There are automated ways to do so though.
An AMD GPU might be more future proof though, e.g. Metal support is way ahead of Nvidia.
The 8800GT is prone to failure, so it's quite likely that any "new" used GPU using that chip will fail again soon. I'd suggest moving on to a more recent GPU, e.g. a Kepler series Nvidia card.
You'll find more details on using a PC GPU in genuine Macs @ MacRumors forum.
Nvidia Kepler or Maxwell GPUs should do it, a recent Pascal GPU requires a newer OS version. If you don't need lots of power I'd go for an older Kepler GPU because of its native support (e.g. GTX 680/770).
Older AMD GPUs such as R9 280(X) should also work fine.
Working link is in this thread: https://www.tonymacx86.com/threads/nvidia-releases-alternate-graphics-drivers-for-macos-high-sierra-10-13-3-387-10-10-10-25.243857/
Be aware that this driver causes lots of trouble for most users (e.g. heavy UI lag).
AMD GPUs have reached a recommendable state just a few weeks ago (basically with the discoveries related to RadeonDeInit, solving "boot to black screen" and "black screen after wake" issues). Your GTX 970 definitely was the best choice back in the days you've build your rig.
Just updated the 1st post to remove some deprecated information. Additionally here's a recent framebuffer dump. Can someone verify that Kamarang and Iriri work fine on Vega?
Exmoor (6) @ 0x10c6e0
LVDS, LVDS, DP, DP, DP, DP...