What Are PCIe Slots on a Motherboard?

PCIe slots on a motherboard are used for various purposes, to connect various devices to the computer. They are faster connections than external connections and usually allow external input through them.

My name is Anthony, and I have been working with computers for 8+ years. This experience has led me to use a variety of devices, including those installed through PCIe slots. I have built multiple systems and had to install devices within the PCIe slots, as well as troubleshoot them.

In this article, we will be discussing what PCIe slots are, why we use them, and what you can plug into them.

Key Takeaways

  • PCIe slots are used to connect devices directly to the motherboard.
  • You can plug many different kinds of devices into a PCIe slot.
  • The slot only matters based on size.

What Are PCIe Slots?

PCIe slots on a motherboard are interfaces to connect devices to the computer through the motherboard. PCIe stands for peripheral component interconnect express.

In order to go into further detail, there are several ways to connect things to a computer. You can connect devices via USB, SATA cables, ribbon cables, HDMI, DisplayPort, and more. The main downside to these methods is the speed.

When transferring data to and from a computer, there are limitations to the speed based on the method used. Certain types of cables will be slower than others, and they are all inherently slower than being connected directly to the motherboard.

This is because it takes time for the computer to receive the signal over the further distance introduced by the cable length. Although it may not seem like much of a delay to humans, in a computer the extra seconds can cause it to slow operations down considerably.

There are several different sizes for these slots. PCIe can come in x1, x2, x4, x8, x12, x16 and x32 slots. These match up with how many lanes are used for transmitting and receiving data, and can affect what you can plug into a PCIe slot.

What Can You Plug Into Them?

There are many different devices that you can plug into a PCIe slot, but they are all known as cards. They connect by pushing the card into the slot fully.

These devices include WiFi cards, RAID cards, graphics cards, Solid State Drive add-on cards, and more. All of these devices can be connected through other methods, but since PCIe is directly connected to the motherboard it will be the fastest method.

Why Use a PCIe Slot?

The main benefits of using a PCIe slot are that it has higher data transfer speeds, higher bandwidth, lower latency, and convenience.

For example, a graphics card is not something you will regularly remove from your computer. Putting it into a PCIe slot will fix it in place, and allow you to easily plug displays in and out of your computer. 

Another example would be WiFi cards. This is also not something that will be changed often and having it out of the way inside your computer may be the optimal place, rather than having it attached via a USB port outside of the computer.

In some cases, it is not possible to have a device connected another way. While USB-C is fairly new and can be used to connect some graphics cards, it is still optimal to connect a graphics card to PCIe due to speed. 


You might be curious about these questions as well, I’ll briefly answer them below.

What to do with extra PCIe slots?

You can always use extra PCIe slots for other types of cards. If you have no other use, then you can plug a USB card into it. This will give you extra USB ports, for a low price and you won’t have to worry about running out of them.

What Is the Difference Between PCI and PCIe?

The main difference is in the appearance and capability. The PCI slot will look different and will be bigger than a PCIe. It is also older than PCIe, as PCIe is an improvement on PCI. There is also a speed difference, with PCIe being much faster than PCI.

Does It Matter Which PCIe Slot You Use?

The device you are plugging in can sometimes change which slot you would use. If you have an x16 device, you would want to plug it in the right size slot. The same goes for a x1 device.

Wrapping Up

PCIe slots are helpful and used to plug in a variety of devices. They are probably one of the more versatile inputs that a computer has, and allow you to access your devices with much greater speeds than other input forms.

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