Question How can I use 2 GPUs on motherboard with only 1 PCIE x16 slot?

[kanturuand]

Do PCIE splitters help using 2 high-end GPUs on 1 PCIE x16 slot on motherboard at their full performance? Have 2 RTX A4000 or 1 A4000 and 1 new RTX 4080 in mind, so I can run 2 of them with the same 16gb VRAM.
They are all high-end cards so I'm afraid splitting the PCIE x16 slot into 2 wouldn't be enough for them. Unfortunately, my motherboard only has 1 slot because Asrock cut out some features for a cheap price BCLK overclock board (the Asrock PG Riptide B660M).

 

[rgd1101]

no

 

[BFG-9000]

PCIe bifurcation requires BIOS support.

A low-powered card can be run in an x4 or x1 slot by carefully breaking off the back of the slot to make it open-ended, but this is limited to 25w of bus power.