Looks, like Gigabyte enables full CSM support on this board
Gigabyte Z690 UD DDR4 (rev. 1.0)
with Bios F5.
"Add Legacy Game Compatibility Mode option"
I will test this board with 12900k cpu in next days for XP SP3 boot
Dietmar
@Gelip
Before I get nuts, I go back to my Asrock z370 Fatalty gaming K6 board.
Oh..what a nice board. At once normal Windbg works through its internal COM1 port.
Tomorrow I try your methode on this board with one after the other of all my PCIe serial slot cards. By the way, I just ordered your Card PCIe Sunix SER5427A also
Dietmar