The Serpent Rider wrote on 2023-03-25, 19:12:
Not between PCI slots. First slot will always take priority.
Well, that's a choice of the BIOS. The BIOS enables the first VGA-compatible card it finds and ignores all other VGA-compatible cards, so they stay in the disabled state. Technically, it is perferctly possible to disable the graphics card initialized by the BIOS, replace the ROM image in shadow RAM, enable the other PCI graphics card and go on with that card. Practically, this is going to fail if something already took pointers into the old BIOS that is going to disappear, it will be troublesome if EMM386 already mapped UMB/EMS at C800:0000, and the new graphics BIOS is more complicated than the old one, but it's definitely not impossible to create a BANSHEE.SYS that can be loaded with ?DEVICE=BANSHEE.SYS from the first line in config.sys to switch over from the Geforce to the Banshee (or the other way around). That driver would be chipset specific, though, as rewriting the shadow RAM is a chipset-specific operation.
I alreday did operations like that when I played around with overly new PCI graphics cards in 486 boards.
Adding a PCI graphics card selection functionality to the BIOS would also be technically possible, but as this is a completely new feature, patching it on a binary level into a BIOS that is already fully assembled is going to be quite a hassle.