My board works with 98SE. It's not news, rloew uses his Z170 motherboards with 98SE as well.
Currently it's running off the integrated Intel HD 610 GPU from the Pentium G4560 with the VBEMP generic driver. It's good for what it's worth, consideting it's limitations.
I use a USB keyboard and mouse.
The Ethernet card, as I've wrote in my previous posts, works flawlessly with the 2008 98SE driver from Realtek's website, the screenshot shows that clearly.
No Audio, but buying a cheap Chinese USB Audio Card should work.
I'm planning on getting a 7900 GTO. (same as 7900 GTX but with lower memory clocks, the PCB and cooler are identical)
I also must consider on getting a normal HDD, (a 1TB Toshiba should be fine, with the partition limited), because now, I'm running 98SE from my SanDisk Ultra USB 3.0 32GB flashdrive (plugged into a USB 2.0 port).
I use the Rufus utility to create a MS-DOS bootable stick (can't do it on Win10, I had to use the free virtual machines MS provides), then I copy the Win98 folder from the 98SE CD onto it (and remove fluff from USB stick that Rufus creates except for IO.SYS and COMMAND.COM, obviously). Then I boot from it, run "setup /is /ie /iv /iq /im /nr /p i" and let the first part complete. (it completes with no errors)
Then I copy the Vcache patch by Xeno to SYSTEM/VMM32, and the HIMEMX.EXE file to root. I put HIMEMX.EXE into CONFIG.SYS with the /MAX parameter in bytes (I've used 512MB, but 1GB should work too). Those two things make it so that I don't have to modify SYSTEM.INI to get to the second part of the install.
Then I finish the second part (it might freeze, but a restart fixes that). After it boots. I've installed the VBEMP driver, and the LAN driver, also copied the latest portable version of AIDA64 to showcase the PC specs. And that's pretty much it. This is the only method I've tried that works...and I've tried A LOT!
Of course the USB drive works entirely in 16-bit DOS compatibility mode (Windows complains a lot in system properties), so any file operations hang the system for a good while. It is REALLY annoying!
And of course, I've turned Legacy USB, CSM, XHCI Hand-Off, PS/2 Emulator all ON.
So as you can see, it's not perfect, but with a few purchases, I might have the world's fastest 98SE build with the best 3DMark scores, we shall see...Maybe I won't have to buy the SATA or NVIDIA patch at all.
I know there's no Legacy SATA option in the UEFI. So maybe the SATA patch will be a necessity...or I develop one on my own
This is my only PC, normally it runs Win10 on a 240GB SSD. (will back to Win7, since Win10 is getting on my nerves more and more with every day). I obviously won't install 98SE on it, I could in theory do a multi boot with Win7/Win98SE once I get the 1TB HDD, but I would have to switch the GPUs for every OS. (I'm getting a GTX 1050 Ti), and that takes (albeit not much) time... Also, almost all of the 1TB space would be wasted.