What Is The PCIe x16 Slot?

The PCIe x16 is a motherboard slot with 16 data links. This slot is known to have the highest throughput rate and can be used with different expansion hardware with higher bandwidth requirements such as graphics cards.

For this article, we’ll go over what the PCIe x16 is, what it can do, and the different PCIe generations.

The Concept of PCIe x16

PCIe stands for Peripheral Component Interconnect Express, and is also referred to as PCI Express. PC builders will usually determine what kind of PCIe slot a motherboard has when they’re purchasing graphics cards.

Most of the modern motherboards released in the market today are customizable. But two interfaces that are considered to be crucial by a lot of the builders in the industry are the SATA and PCIe interface. SATA interfaces are designed for hardware with lower bandwidth requirements such as storage drives. PCIe interface handle the high speed devices.

Motherboards will come equipped with different sizes of PCIe slots. If this is too much for you, don’t worry. There are only two things that you need to keep an eye out when you’re buying graphics cards: the PCIe slot it uses and the available PCIe slots you have on your motherboard.

What Does A PCIe x16 Slot Look Like?

Image: A typical x16 slot.

A PCie x16 slot can be easily identified by its size on the motherboard chipset. All you have to do is look for the largest slot on there, as seen on the image aboev.

A PCIe x16 slot measures at about 89mm in length and contains 82 pins, with each pin serving a unique purpose. On the opposite side of the spectrum, we have the PCIe x1 slot and is the smallest sized PCIe slot in the motherboard. It only measures 25mm in length and has 18 pins.

The PCIe x16 is the largest slot found on a motherboard.

A proper x16 slot with 16 lanes measures 89 mm in length and has 82 pins, each serving a purpose, such as providing power and transferring data.

In contrast, the most undersized slot, PCIe x1, has 18 pins and measures 25mm in length.

What Is The PCIe x16 Slot Used For?

As mentioned earlier, your graphics cards are installed into the PCIe x16 slots, primarily because graphics cards transmit the most amount of data. It goes without saying that the GPU goes into the slot that can accommodate higher bandwidth.

What Does The 16 Stand For After The X?

The X denotes the number of PCIe lanes a PCIe slot has. For example, a PCIe x1 contains 1 PCIe lane and a PCIe x4 contains four lanes and so on.

However, a PCIe x16 doesn’t necessarily mean it contains 16 lanes, and we’ll get to that in the next section.

You also have to remember that there’s a difference between x16 and True x16 slot. A slot with a physical size of an x16 slot may only contain 4 or 8 lanes. As the name implies, a True x16 slot contains 16 lanes and is found in modern motherboards. A PCIe x16 slot that doesn’t contain 16 lanes are used for smaller pieces of hardware like an NVMe SSD expansion card or storage drive. Your graphics cards are installed on the True x16 slot.

What Are The Different Types of PCIe Slots?

In order for us to understand the functions of a PCIe x16 slot, we’ll need to understand the different types of PCIe slots and what they’re commonly used for.

PCIe x1 Slot

We mentioned prior that the PCie x1 slot is the smallest PCIe slot on a motherboard chipset, while the x16 slot is the largest. The PCIe x1 slot is used for modems, sound cards, and other port expansion cards.

PCIe X4 Slot

Up next we have the PCie x4 slot. This slot contains 4 PCIe lanes and is used for some higher bandwidth hardware like 10G Network Cards and NVMe SSD expansion cards.

PCIe X8 Slot

The PCIe x8 slot contains 8 PCIe lanes and is used for secondary graphics cards. Builders often look for motherboards that have a PCIe x8 slot so they can use two graphics cards. The x8 slot is also used for RAID controllers or RAID cards.

What Are The Current PCIe Generations?

A PCI express standard will come in five generations: PCIe 1.0, PCIe 2.0, PCIe 3.0, PCIe 4.0, and PCIe 5.0. Newer generation has double the bandwidth compared to the previous ones.

What’s New With PCIe 4.0?

The PCIe 4.0 standard was introduced in 2017 and has 64GBPs throughput. This particular PCI express standard generation is used primarily by enterprise-grade servers. But in 2019, they were able to accommodate SSDs. That same year, the AMD Ryzen 3000-series processors were the first desktop CPUs to support PCIe 4.0 x16, provided their users ran with an X570 motherboard chipset.

What’s New With PCIe 5.0?

Two years after the PCie 4.0 was introduced, the PCIe 5.0 debuted into the market. The new PCI express standard generation came with 128GBps fo throughput and backward compatibility with previous generations.

PCIe 5.0 also contains features such as improved electrical workings that allow for backward-compatible CEM connectors. This time, Intel was the first to accommodate the PCIe 5.0 out of the box with its Alder Lake architecture.

Are There Future PCIe Generations?

PCIe 6.0

PCI-SIG released the standards for the PCIe 6.0 in 2021, but we won’t be expecting to see any products working with PCIe 6.0 until late 2022 or early 2023.

PCIe 6.0 will have about 256GBPs of throughput, double that of the PCIe 5.0. It’s also mentioned that the data transfer rate will reach 64 GT/s per pin, double that of the PCIe 5.0’s 32 GT/s per pin. And yes, PCIe 6.0 will be backwards compatible