What is PCIe? Work Process, Pros, Cons & More

What is PCIe?

PCIe or PCI Express is the abbreviated form of Peripheral Component Interconnect Express, which is a form of computer bus expansion interface that can be used to add several useful components into your PC like a second GPU, WIFI adapters, SSD drives, RAID cards, etc.


  • PCIe offers much larger bandwidth and higher data transfer speed due to the higher number of lanes.
  • PCIe offers more utility and less latency.
  • The power consumption of PCI express is higher than usual which results in faster battery drain in laptop computers.
  • PCI express is expensive and lacks specialization.
  • PCIe only supports modern devices.

Understanding PCIe (Peripheral Component Interconnect Express)

What is PCIe

PCIe establishes high-speed connection and offers high bandwidth during data transfer.

It is a very important component that starts working as soon as you switch on your computer.

It determines the peripherals connected to the motherboard and their interconnections.

This helps in creating a roadmap of the traffic of the link as well as in negotiating the width.

The PCIe slots connect expansion cards. The data packets move through the lanes in them.

There are two pairs of wires in every lane for sending and receiving data separately at one bit per cycle.

PCIe may come in different formats which may be quite difficult to understand if you do not know what the two sets of numbers signify.

The x1, x4, x8, or x16 denotes the size of the PCIe with respect to the number of pins.

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The other part may be 1.0, 2.0, 3.0, or 4.0 which denotes the bandwidth supported by each PCI Express lane, usually measured in GB/s.

Almost all high-end motherboards today come with PCI Express slots that can be used for different purposes such as for connecting Wi-Fi cards, RAID cards, GPUs, and SSD add-on cards and more.

Brief History of PCIe

The PCI was introduced as a computer bus interface in 1991 and has gone through many improvements since then.

It is, in fact, the forefather of the PCIe cards we are talking about today, and thus share a common history.

Now the PCI Express has been in use since 2001, and the very first PCIe 1.0a had a speed of 250 MB/s per lane and transfer rates of about 2.5 GT/s (here GT refers to GigaTransfers).

Then two other versions were launched by 2010, and the most used version today is PCIe 3.0.

Newer versions are also present like the 4.0 and 5.0, while you may also come to know about the 6.0 within 2022.

How Does It Work?

As said above, the PCIe has different lanes for data transfer. The more number of lanes, the greater is the bandwidth, and hence the faster it is.

Though universal, PCIe is available in different physical forms. This refers to x1, x4, x8, and x16 lane types.

Each of these cards has different ports on themselves, while also there are different ports on the motherboard.

But, the good thing is that you can use an x8 GPU in an x16 slot, and vice versa.

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In the second case, however, the GPU will have to work in a lesser bandwidth.

The PCIe works like a network, with a point-to-point connection. Check out difference between PCIe and SATA.

This means that data moving out from the main bus goes through a switch, and then gets separated in a different direction towards the various devices that have asked for this data.

How Fast is PCIe?

Each lane on a PCIe 3.0 can reach speeds up to 1000mb/s.

The total speed and bandwidth of an x16 PCIe card is about 16 GB/s and 32 GB/s respectively, and now you know why your GPU requires this lane for functioning.

While some GPUs work in the x8 slot, adding your GPU to the x16 lane would provide you the best performance.

Pros of PCIe

1. Larger Bandwidth

PCIe cards have up to 16 lanes for data travel, and this offers greater bandwidth. Thus, even high-performance GPUs can be fitted in PCIe slots.

2. Better Speed

In terms of speed, the PCIe is much faster than SATA and you will notice this difference as soon as you add the same SSD drive, first into the PCIe slot, and next in the SATA slot.

To be exact, the max speed in a PCIe 3.0 SSD is about 16Gb/s, while the SATA III can only reach up to 6 Gb/s.

Newer PCIe iterations like the PCIe 4.0 are even faster, but the upgrade will cost you.

3. More Utility

The PCIe interface can be used to add not only video cards but also WIFI adapters, SSD drives, etc and are thus multi-purpose.

4. Less Latency

Along with high speed, PCIe reduces the latency in a system.

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They have a direct line to the peripheral components and so, while accessing large files or while working on servers and playing games, it is very useful.

Cons of PCIe

5. Greater Power Consumption

Although nothing too much, PCIe SSDs tend to consume more power when used for a long time.

This is also why using a SATA SSD on a laptop gives you a bit more battery backup.

6. Supports only newer devices

Most of the older computers will not support a PCIe SSD, and here the SATA interface comes handy with better support for older PCs.

7. Lack of Specialization 

The PCIe can carry different types of data, but it doesn’t have a specialization.

It doesn’t have standard storage commands like the other interfaces, which may pose problems.

8. Expensive

A principal drawback with the PCIe form of storage is that it is very expensive. For a budget buyer, it is not always possible to afford such an expensive SSD drive.


Now you know about PCIe, put it to you as simply as possible. Share this article and let us know whether this was helpful.

About Puja Chatterjee

Puja ChatterjeePuja Chatterjee is a technical writer with extensive knowledge about computers. She graduated from BIMS. Her expertise includes technology writing and client relationship management gained through over 12 years of experience. Follow Her at Linkedin.

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