motherboard slots

Since you can use a mATX motherboard, you do get more flexibility than an ITX motherboard, such as getting 4 RAM slots and a pair of PCIe slots rather than being limited to one.

Motherboard for Z400 Workstation 6 DIMM memory slots | sieuthimaychu

You can typically identify the types of expansion slots available on your computer by looking at the motherboard documentation or by physically inspecting the motherboard itself.