What is PCI and PCIe

Expansion cards became available when IBM launched their first PC in the market. These expansion cards came as a significant boost to the computing system since the expansion added dozens of new features to the computer. One such is the Peripheral Component Interconnect (PCI) that was introduced during the early 90s. Since then, IBM released multiple different versions of the PCI, with the latest version slated for a late 2021 release. 

As a result, PCI is not a new technology. While the PCI Express may have replaced the original PCI slot in modern-day computing, you must have knowledge about both of them. The PCI was a significant boost since it provided a major improvement over all the previously existing slots on the motherboard. It quickly rose through the ranks and became the most dominant slot on the motherboard. As PCI slowly started getting recognition, the manufacturers too increased the number of PCI slots on their motherboards.

Although the development of PCI cards brought in a radical change about the overall working of expansion cards, there is still more to it than what meets the eye. The PCI is one of the most vital components of your motherboard. Therefore, it is essential that you know everything there is about PCI and PCI Express expansion cards. In this article, we will be giving you detailed information about PCI, PCI Express (PCIe), and everything there is to PCI and PCIe. 

What is PCI?

What is PCI

PCI stands for Peripheral Component Interconnect, which are used as expansion slots in our computer’s motherboard. The PCI was first introduced during the 90s and is used to connect integrated chips to the motherboard via expansion cards.

In simple words, the PCI acts as a pathway for communication between the motherboard and other devices. These PCI slots are required to attach/insert additional cards to your system, such as a LAN card, sound card, capture card, or a TV tuner card.

These PCI slots are designed in the form of expansion slots eliminating the use of cables whatsoever. This is the most common way of attaching add-on controller cards and pairing other external devices with your system’s motherboard. As of today, you will find three PCI connectors on your system, referred to as USB slots. Inserting a card on the PCI slot on the motherboard provides additional I/O ports to the back of your computer. Since the primary function of the PCI bus is to facilitate communication between the motherboard and its components, it is not as fast as the system bus. 

How Does PCI Work?

The PCI is a 32-bit bus which means that it has 32 lines to transmit several data simultaneously at a good pace. The CPU is the most essential component of every motherboard. For the motherboard to function correctly, it is vital that all the components are in sync. This is where the PCI comes in. The PCI is responsible for ensuring that all the motherboard components are working efficiently. The task of the PCI is to provide sufficient bandwidth to all these components to ensure an efficient connection with the system. The PCI driver allows the PCI device to function as intended. 

For example; The PC monitor is attached to the CPU using a graphics card. Here, the PCI supplies enough bandwidth for the connection to be successful. 

Peripherals that can be used with PCI Slot

Every external device is connected to your system via the PCI slot. The system then scans the device attached to the PCI slot and accordingly provides you options on your monitor. There are numerous peripherals that are put to good use via the PCI slots, such as 

  • Modem
  • Network Card
  • Graphics Card
  • TV tuner
  • Firewire cards
  • Controller Card
  • SSD
  • HDD
  • USB
  • Scanner
  • Sound Card
  • Removable and other external devices

The introduction of the PCI brought in a radical change about the overall working of expansion cards, majorly because of its Plug and Play feature. Meanwhile, PCI allows for automatic resource configuration. Instead of manually configuring your expansion cards, these cards now automatically requests for the resources it needs

What is PCIe?

What is PCIe

Though the PCI was quite popular, the speed limiting needed to be looked at. In order to address the speed limiting problems, the PCIe slot was introduced. PCIe stands for Peripheral Component Interconnect Express (PCIe), that is a motherboard expansion that was launched back in 2003.

The PCIe enables high-speed serial communication between the CPU and all the other components of a motherboard. Today, the PCIe has surpassed the PCI to become the primary expansion bus and a popular communication pathway for many other onboard applications and devices. 

The primary reason behind introducing PCIe was to enable a higher data transfer rate and simplify the overall system design. Since then, the PCIe standard has iteratively improved over time. Each new generation was designed explicitly to accommodate the latest bandwidth requirements of the modern computing system. The key feature of the PCIe is the added lanes from 1 to 32 to increase its throughput. PCIe uses serial communication, unlike the PCI, which uses a shared bus for communication between the CPU and other peripherals.

Peripherals that can be used via the PCIe Slot

The majority of the devices pair well with the PCIe slot. Some of the devices that use the PCIe expansion slot for elevated data transfer include

  • Graphic Adapter Cards
  • Network Interface Cards (NIC)
  • Storage Accelerator Devices
  • TV Tuners
  • Video Cards
  • Wi-Fi 
  • RAID Controller Cards

PCIe 1.0 vs 2.0 vs 3.0 vs 4.0 vs 5.0 

Following the release of PCIe 1.0 in 2003, there have been over 4 more generations in the market, with the the PCIe 4.0 latest amongst them. With 4.0 generations out already, the PCIe 5.0 is all set to hit the market in the later half of 2021. 

Meanwhile, here is a detailed comparison chart noting down all the specifications and other differentiating factors between the PCIe 1.0, PCIe 2.0, PCIe 3.0, PCIe 4.0, and PCIe 5.0

GenerationRelease YearRate Of TransferBandwidthLane ConfigurationBandwidth x16
1.020032.5GT/s2 Gbps250 Mbps4 Gbps
2.020075GT/s4 Gbps 500 Mbps8 Gbps
3.020108GT/s8 Gbps1 Gbps16 Gbps
4.0201716GT/s16 Gbps2 Gbps32 Gbps
5.0201932GT/s32 Gbps4 Gbps64 Gbps

PCI Express 1.0

The PCIe 1.0 was introduced back in 2003 and comprised of some big names in the game, such as IBM, Dell, HP, AMD, and Nvidia. The PCIe 1.0 delivers a maximum data transfer speed of 2.5GT/s in an encoded serial bit rate. Meanwhile, the 1.0 is designed explicitly to support a bandwidth of 2 Gbps with a throughout of up to 250 MB/s. While it uses an 8b/10b encoding scheme, the PCIe 1.0 supports total bandwidth of 4 Gb/s.

PCI Express 2.0

Following the PCIe 1.0, the PCIe 2.0 was released in 2007 that uses a line code 8b/10b. In contrast to the PCIe 1.0, the PCIe 2.0 supports a transfer speed of up to 5 GT/s. It is designed explicitly to support a bandwidth lane direction of up to 500 Mbps. If you look carefully, you will notice that the PCIe offers double the data-transfer rate and throughput as compared to the PCIe 1.0. It provides a per-lane throughput of up to 500 MB/s, whereas it is fully supported by chipsets. 

PCI Express 3.0

The PCI Express 3.0 was released in 2010 and came with numerous architectural improvements. The speed of the PCIe 3.0 is relatively similar to the 2.0. However, the PCIe 3.0 offers a faster rate of communication in contrast to the 2.0. Along with architectural improvements, the PCIe 2.0 also comes with numerous protocol management improvements unlike the 2.0. It offers a whooping data transfer speed of up to 1 Gbps. Every modern-day motherboard is fully compatible with the 3.0 and well supported by Intel CPUs. In addition, the 3.0 features an interconnected bandwidth of up to 8 GB/s with a bandwidth lane direction of 1 Gb/s. 

PCI Express 4.0 

The PCI 4.0 is the last of the expansion slots to get a commercial release. Launched back in 2017, the PCI Express 4.0 offers double the bandwidth than the 3.0. It has a data transfer rate of 16GT/s and 2 Gbps lane configuration. It uses the line code 128b/130b and supports a bandwidth lane direction of 1Gbps with each lane supporting double the bandwidth as compared to the 3.0. Also, the PCI express delivers high-performance 16 Gbps data rates with a flexible lane width configuration, all while consuming low power. The 4.0 is backwards compatible meaning you can use it on a motherboard that has PCIe 3.0 slot. 

PCI Express 5.0

The PCI Express 5.0 is the latest of the expansion interface that was launched back in 2019.  The 5.0 is a subsequent extension of the PCIe 4.0 that offers double the bandwidth, data-transfer rates, and frequency in comparison with all the previous generations. It is fully backwards compatible allowing you to pair it with motherboards having either 1.0, 2.0, 3.0, and 4.0 slots respectively. With the PCIe 5.0, you are looking at a higher data transfer speed of about 32 Gbps and a 128 Gb/s bandwidth in a 16-lane configuration. 

Types Of PCI Express Slots

PCIe Versionx1x4x8x16
1.0250 Mbps1 Gbps2 Gbps4 Gbps
2.0500 Mbps2 Gbps4 Gbps8 Gbps
3.01 Gbps4 Gbps8 Gbps16 Gbps
4.02 Gbps8 Gbps16 Gbps32 Gbps
5.04 Gbps16 Gbps32 Gbps64 Gbps

Every modern-day motherboard is equipped with latest of one of these PCI Express expansion slots. Meanwhile, some of the latest computing models possess both PCI and PCIe slots on their motherboards. These PCIe slots use serial communication instead of a bus, thus offering upto 30 times the I/O of the PCI bus. The slot length determines the amount of data that can be transferred. 

Though PCIe slots are universal, they are available in a variety of different physical configurations. The most common PCI Express cards are 1x, 4x, 8x, and 16x. All these expansion cards tend to have a different slot on their respective card and occupy different slots on the motherboard.

PCI Express x1

PCI Express x1

The PCIe x1 is a high-speed serial computer expansion bus standard that was introduced as a potential replacement to the PCI expansion slots. In PCIe x1, data is allowed to move within the motherboard. However, there isn’t much purpose for this slot other than just being used for LAN and SATA cards. This slot has a single lane that moves data around at a speed of 1 bit/cycle. The maximum bandwidth offered by this PCI card is 250 MB/s .

PCI Express x4

PCI Express x4

With each new generation, the bandwidth slot doubles in configuration. The PCI Express x4 is a 4th generation expansion card that comes with a 4-lane configuration. In comparison with the PCI Express x1, the PCI Express x4 offers a bandwidth of 1000 MB/s. This four-lane card provides a significantly better performance than the PCI x1 slot. 

PCI Express x8

PCI Express x8

In the PCI Express x8, each lane can achieve data-transfer speeds of 250-1969 MB/s. This 8-lane express card provides significantly better performance than the PCI Express x4

PCI Express x16

PCI Express x16

The PCIe 16 comes with a 16-data lane and is almost 29 times faster than the traditional PCI video card. It is capable of achieving data transfer rates of 4000 MB/s. This slot is generally used solely in video cards since video cards require a potentially high bandwidth.

Note: The bandwidth is purely subjected to software compatibility and limitations. Therefore, a higher bandwidth does not mean better performance.

How To Find Out Which PCI Slot You Have?

Often there will be times when you will need to know the PCI slot your motherboard has. However, it is always tricky to find the exact specifications of any device. Though the overall motherboard specification is available on the user guide, many do not have access to the user guide. If you are one of them, then we have you covered. Two different ways are using which you can find out which PCI slot you have.

1. Check It Manually

In such cases, Google can be of great help. A simple google search can help answer the toughest of queries. To check your PCI slot manually, follow the steps given.

  • Find the model number of your computer/laptop (The model number is generally located at the back of your Desktop cabinet or on your motherboard)
  • Once you locate the model number, open your Internet Browser
  • Open Google
  • Type in your “model number”
  • Search for the PCI slot

If you are unable to locate your device’s model number, go to the company’s website. Put in the name of the device you are using. Once you type in the model name, specifications would appear. Select the specifications as your device. When your device’s specifications are in place, you will get to know the PCI slot installed on your motherboard. 

How To Find Out Which PCI Slot You Have

If none of the above-mentioned method is working for you, reach out to the company’s customer support executive to help you out. Several manufacturers have a solid customer-service that generally respond within 24-hours. 

2. Using Third-Party Software

If the Google search or customer support does not yield you any results, then using a third-party software can take care of your troubles for you. Software such as the Belarc Advisor builds a detailed report of your installed software and hardware and accordingly displays the right results in your browser. 

In addition to the installed hardware and software information, this software can also help you keep track of your network inventory, security updates, antivirus, and other security anomalies that may or may not be present in your system. Meanwhile, you can use the Belarc Advisor to find out which PCI slot is equipped in your motherboard. Note that the data collected during this process is entirely PRIVATE and the software is only designed for PERSONAL USE

Click the following link to download the Belarc Advisor: Belarc Advisor Download

Conclusion

We hope our article successfully walked you through what PCI and PCIe slots are and how they work. These expansion slots are a vital component of your motherboard which is you must have information about them. As technology evolves by the minute, computer manufacturers tend to take their time to standardize their systems with the latest PCIe Express generations. 

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