Types of Motherboard Form Factors -

In computing, an expansion card is a printed circuit board that can be inserted into an electrical connector, or expansion slot on a computer's motherboard

Memory Types Up to DDR5 4800 MTs Up to DDR4 3200 MTs; Max # of Memory Expansion Options Direct Media Interface Revision ; Max # of DMI

expansion slot There have been several types of expansion slots over the years, including PCI, AGP, AMR, CNR, ISA, EISA, and VESA, but the most popular one

expansion slot drawing If not limited to 'expansion card work electrically with PCIe interface in the slot' then more weird things can be put into it For example fan