What is PCIe (Peripheral Component Interconnect Express)?

In addition to standard motherboard components, computers often need to be equipped with other parts and components to achieve the desired functionality.

In this blog, you'll learn more about what PCIe is, the different components, and how it helps enhance a computer's capabilities to maximize efficiency at the edge.

What is PCIe?

PCIe, or peripheral component interconnect express, is an interface standard for connecting high-speed input output (HSIO) components.

Every high-performance computer motherboard has a number of PCIe slots you can use to add GPUs, RAID cards, WiFi cards, or SSD (solid-state drive) add-on cards. 

The primary benefits of PCIe are that it offers higher bandwidth, faster speed, lower latency, and more utility. 

The number of PCIe slots depends upon the type of motherboard that you buy. 

How do PCIe slots work?

PCIe slots come in different physical configurations: x1, x4, x8, and x16. The number after x tells you how many lanes (how data travels to and from the PCIe card--more on that later) that the PCIe slot has.

For example, a PCIe x1 slot has one lane and can move data at one bit per cycle. A PCIe x2 slot has two lanes and can move data at two bits per cycle.

Let's take a look at the different types of slots:

1. PCIe x1: These are the smallest PCIe slots, used for almost any other cards like average network adapters and USB expansion cards. 
2. PCIe x4: These have four PCIe lanes, and they also can fit into a x16 slot. Often used for single M.2 NVMe SSD expansion cards, they are also used for SATA 3 expansion cards and high-speed network adapters. 
3. PCIe x8: These can also fit in an x16 slot, but they have half the PCIe lanes and are most commonly used for GPUs or for M.2 NVMe SSD expansion cards. 
4. PCIe x16: The largest slots on the motherboard, these slots are used for cards that require a high bandwidth like GPUs. 

By far, the most popular set up is PCIe x16, as most GPUs require it to operate at their full potential.

There are two components to a PCIe slot: mechanical (cards) and electrical (lanes). For instance, you can have a slot that is x16 mechanical that is x8 electrical, meaning that you can house 16 cards, but it can only support 8 lanes which may lead to lower performance. 

Additionally, you can insert x8 mechanical into an x8 mechanical and x4 electrical for half the performance. 

What is a PCIe card?

A PCIe card or expansion card is just another name for hardware that can be added to your device through PCIe slots. 

What is a PCIe lane?

PCIe lanes are the physical link between the PCIe-supported device and the processor/chipset. 

PCIe lanes consist of two pairs of copper wires, typically known as traces, that run though the motherboard, connecting the PCIe-enabled device to either the processor or motherboard chipset.

Think of a PCIe lane as a highway where the vehicles--or in this case, data--travel in both directions at the same time.

Up to 32 of these bidirectional PCIe lanes can be allotted to a single device, enabling it to achieve a high-bandwidth, low-latency transfer of data. 

The different variations of PCIe

PCIe standard currently comes in five different generations: PCIe 1.0, PCIe 2.0, PCIe 3.0, PCIe 4.0, and PCIe 5.0. The bandwidth doubles with each generation. 

PCIe 6.0 is set for release either by the end of 2022 or early 2023. 

Below is a chart comparing the capabilities of the different generations of PCIe: 

What can you plug into PCIe slots? 

There are many devices that can be plugged into PCIe slots: 

GPUs (Graphics Processing Units) 

GPUs are one of the most common components plugged into PCIe slots. These are processors that allow all the visuals to be produced, and they are also equipped with enhanced artificial intelligence capabilities. 

The only way to add a GPU is via a PCIe x16 slot because, as mentioned previously, the majority of GPUs are designed to utilize 16 PCIe lanes, and they require the full PCIe x16 slot to be fully functional. 

Ethernet Network Cards (NIC cards) 

While most motherboards come with Ethernet support, older motherboards may not have it. 

For those older motherboards, then, investing in ethernet network cards, or NIC cards, may be a good idea.

On mainstream motherboards, you only get average gigabit network speeds, but with NIC cards, you get 10G or faster speeds. 

SATA Expansion Cards

PCIe slots can also be used to increase storage capacity. If you have a limited number of SATA ports on your motherboard for connecting SATA drives, a PCIe SATA expansion card may come in handy. 

The size of the SATA expansion card and the type of slot it requires depends on factors like how many SATA slots it has and whether or not it has a RAID controller. 

SATA expansion cards are available for PCIe x1, x4, and x8 slots. 

M.2 NVMe Expansion Cards

PCIe NVMe SSD are the fastest hard drives available. 

Many newer motherboards do come with at least one NVMe M.2 slot, but if your motherboard lacks the M.2 slot, or if you want to add another NVMe SSD to your system, then you can get an NVMe SSD expansion card. 

Note that each M.2 NVMe slot requires 4 PCIe lanes, and as a result, the smallest one available requires a x4 PCIe slot. 

Riser cards

Riser cards function as PCIe port splitters. Just like port expansion cards, PCIe riser cards add extra ports to your motherboard--in this case, PCIe slots. 

PCIe and Trenton Systems

By enabling motherboards to connect with a computer's most critical components, PCIe helps ensure proper functionality for a variety of technical and performance specifications. 

At Trenton, our team of engineers work tirelessly developing customized motherboards with the latest PCIe to provide our customers with numerous customization and upgrade options.  

We can add NVIDIA GPUs onto our motherboards via PCIe x16 slots. Our 3U BAM, for example, has double-spaced x16 slots for improved incorporation of double-wide GPUs.

We can also integrate our solutions with NIC cards via PCIe to enhance networking, storage, and processing capabilities. 

In addition, our PCIe Expansion Kit allows customers to add another 18 PCIe slots to any open PCIe x16 slot, making room for functions beyond preloaded features like graphics and storage. 

With a variety of configurations and compatible add-ons, PCIe strengthens a computer's capabilities to maximize bandwidth and reduce latency, ensuring optimal performance in real-time. 

• "All Types Of PCIe Slots Explained & Compared" - CG Director