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How Many PCIe Lanes do I Have? – Learn Here

This is a big question that many people building, or considering upgrading their desktop always ask.

If you want to add a new component to any of your PCIe slots, you will need to know how many lanes you have available before you end up adding a component that could be underutilized, or worse still, result in the performance undercut of some other pre-installed components.

PCIe slots are great because they let us connect more devices to our motherboards, letting us increase its functionality. If you’ve been wondering, how many PCIe lanes do I have, read on and find out.

In short, the total number of PCIe lanes you have are determined by your processor as well as your motherboard chipset.

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How Many PCIe Lanes do I Have?

To know the amount of PCIe lanes you have available, you will have to look for:

  1. PCIe Lanes on the Motherboard Chispet
  2. PCIe Lanes on the CPU

This information can be found through their respective specsheet.

PCIe Lanes on a Motherboard

Motherboards are built around a specific chipset. Each chipset has a different architecture and thus has a different number of PCIe Lanes.

Let us look into motherboard PCIe lanes:

Using the Board’s Information

ChipsetHow Many PCIe Lanes do I Have
Shows the Intel Z390 Chipset used in MSI MPG Z390 GAMING PRO CARBON Source: MSI.com

Most motherboards will provide you with information about the chipset being used, amount of PCIe slots as well as how they can be best assigned to devices.

Consulting with your user manual may get you this information or you can even do a quick online search and get the information from a reputable site such as the board’s manufacturer’s website.

PCIe Lanes on a Chipset

DMI motherboard 2
Intel Z390 Chipset with a single DMI link which accounts for a single X4 slot.

The Chipset manages the flow of data between the computer’s CPU, memory and peripheral devices. It also has lanes through which this data gets moved around.

The total lane count on a motherboard will include the number of lanes that are provided by the chipset. But, it should be noted that NOT all motherboard PCIe lanes are available for use by the users. Some are reserved for the prebuilt in controllers and components.

For example, the Z390 chipset has a total of 24 lanes. However, it should be noted that 20 of the PCIe lanes provided here are used by the motherboard components such as USB, Ethernet, audio and other controllers. As a result, 4 are available on the motherboard for the user to use via an X4 PCIe Slot.

Purpose of Chipset Lanes

The lanes on a chipset may not be capable of efficiently handling high bandwidth devices like a graphics card. However, they are quite effective when used for HSIO (High Speed Input/Output) devices with X1 or X4 bandwidth.

These are responsible for some of the computer’s internal connections like SATA, USB and some PCIe storage devices.

Chipset lanes provide a backup for CPU lanes because they operate at a lower latency since there’s no direct connection to the CPU.

Also Read: Best Motherboards for NAS

PCIe Lanes on the CPU

Investing in a motherboard with many PCIe lanes sounds fun until you realize that the number of lanes you can use will depend on several factors.

As stated, the lanes are used to communicate data between the PCIe device on the slot and the CPU or the chipset.

You, therefore, need a CPU with enough PCIe lanes if you’re going to build a very powerful machine that has multiple graphics cards all working at X16 bandwidth.

Since there’s no way to count the lanes on a Processor, this information should be provided by the manufacturer of the device on the user guide or on their website like it’s done for this Intel Core i9-9980X processor (see the section on Expansion Options).

PCIe core extreme lanes
Intel Core i9-9980XE boasts 44 PCIe lanes

What Determines CPU Lane Counts

Most mainstream Intel processors will come with a total of 16 lanes. These are sufficient to run a single graphics card at full capacity. The number of lanes you have on your CPU will depend on the device’s model, manufacturer and purpose.

Take for example, a server CPU like the AMD EPYCTM 7551; it comes with a whopping 128 PCIe lanes. Though this number looks appealing, it may not perform very well for some purposes like gaming.

Plus a server CPU is a highly expensive device and would therefore no be suitable for consumer purposes.

As a general rule, most average processors have 16 PCIe lanes. These include budget processors such as Intel Pentium processors all the way to Intel Core i7 or AMD Ryzen.

The upper echelon of consumer grade processors i.e the extreme processors can offer a much higher number of lanes in the range of 44.

PCIe Slots and Their Lanes

PCIe Sizes
PCIe Slots come commonly in x1, x4, x8 and x16 sizes. X8 size is rarely seen as it is merely replaced by X16 size working in X8 mode.

A PCIe X1 slot only has a single lane. It is useful for devices that do not require high bandwidths such as USB cards.

The PCIe X4 slot, on the other hand, has four lanes that let you transmit four bits of data with every clock cycle. In other words, it can transmit four times as fast more data as the X1 slot.

With an X8 slot, you get high bandwidths still thanks to its 8 lanes; this makes it ideal for RAID cards as well as Graphic cards in cases where an X16 slot is unavailable.

And at 16 lanes, a PCIe X16 slot allows you to connect almost any device and it will work at its maximum bandwidth. It is ideal for use with graphics cards.

What Lanes Say about a Motherboard and a CPU

If you have 16 lanes on your CPU, you will be able to use a single X16 PCIe slot or two PCIe X16 slots working at X8 mode. This is generally done when you have dual graphics cards.

If you have two PCIe X16 slots and a single graphics card then as a rule of thumb, it is always advised to occupy the first PCIe X16 slot it with. Occupying the second PCIe X16 slot clocks down both the PCIe X16 slots to X8 mode.

We mentioned earlier that the motherboard chipset also provides PCIe lanes. If you motherboard provides 4 lanes, you should have a dedicated X4 slot located near the PCIe X16 slots. This slot can be occupied with other expansion cards like Network Cards, RAID controllers etc

The CPU’s lanes play a huge role in determining the usable lanes in a computer. On the other hand, motherboard manufacturers have to keep up with the upward trends by creating boards that can adequately utilize all the lanes the CPUs it supports have.

Conclusion

In this article we tried to answer a common question i.e how many PCIe lanes do I have? Basically, to determine the amount of lanes you have, you have to look at the motherboard chipset as the as CPU specsheets.

PCIe slots let us connect devices to our motherboards to improve their performance. Over the years, this standard has evolved, resulting in improved connections, and more bandwidth through the use of multiple lanes.

The lanes are what connect the peripheral device through the motherboard, to the Processor and so with more lanes, you will get more bandwidth.

Knowing the total number of lanes on the motherboard is important if you are building a desktop. It tells you how many and what kind of expansion slots you can add.

We also recommend you read the following article to get a better understanding:

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