This section will also be short, and to the point. With slots it can be hard to know what you need or how many of each. In this section I will explain what each port and slot is used for, so that you can make an educated decision on which ones and how many you will need. As many motherboards have many and sometimes few pci cards and slots. It can be hard to know if you need a lot of them or just a few.
In order from left to right the slots shown are pcie x1 slot, a pcie x16 slot, and two regular pci slots.
Pci slots were one of the old standards. But as technology improves we are seeing a new standard, pcie. With the new standard cementing itself, users might have older cards laying around that they want to use. Or a card might still use the older standard that you want to buy. To that end most motherboard manufacturers, tend to include at least one of these ports on some of their models. It is wise to know what you will need or want to plug into your motherboard. Maybe pick a motherboard that has one of these slots. Pcie is the one that is replacing pci.
Pcie x1 is one of the new standards. It is replacing pci slots, it is faster, and doesn’t need to take up as much room on the motherboard or card. Everything from some graphics cards, sound cards, internet cards and even video recording cards are used in this slot. It is a very versitile slot to have on your motherboard. Have at least 1 or 2 of these on your motherboard to allow for upgrades. If you plan to have a gaming video card make sure that you do not have one of these under your pcie x16 slot as the graphics card will usually cover it and render it useless as you will not be able to plug anything into it.
pcie x16 are mainly used for graphics cards nowadays. Most users will only need one of these. If you plan on using onboard graphics, then you will not even need to have one of these. But I would recommend having at least one just in case you need or want to upgrade down the line.