atx motherboard expansion slots: Solved: M.2 Slots for Motherboard 8860 A(SMVB). ATX board owners: what are you filling all those expansion .... What Are Expansion Slots? - Lifewire.
The 8860 A(SMVB) motherboard specifications list it as having two M.2 expansion
slots. HP Desktop PCs - Motherboard Specifications, Stark | HP® Customer Support Looking at the motherboard, I'm only able to find one.
ATX is the most common motherboard design. [2] Other standards for smaller boards (including microATX, FlexATX, nano-ITX, and mini-ITX) usually keep the basic rear layout but reduce the size of the board and the number of
expansion slots.
Whether your CPUs,
PCIe slots, and expansion cards support PCIe 4.0 speeds is determined by the CPU manufacturer, motherboard manufacturer, and and expansion card manufacturer, respectively.