This is a multiboot setup with two GPUs: an Nvidia 7000-series card for legacy OSes like Windows 98 and Windows 2000, and an RTX card for Windows 11. There’s room for both in the system. The motherboard is an ASUS Prime X670-P.
Windows 2000 runs with NVMe storage, USB 3.x, and HD/HDMI audio support. (using backported drivers) For Windows 9x, I’ve added a separate PCIe-to-USB adapter and a dedicated sound card.