Do all PCs have a PCIE slot? If they don't, can we upgrade our RAM

PCIe Motherboard pc pcie slot We have systems built with industrial class motherboards and top quality standard desktop PC motherboards Most of our PCI systems also have PCIe slots pcie 4 card in pcie 3 slot PCIe compatibility and performance generates a LOT of confusion In Explaining PCIe Slots

pcieslot Asrock Deskmeet It has a PCIe slot plus room for a ton of storage and a quite capable CPUAPU And it's small