The total number of PCIe lanes you have on your system can range from 30 on an average PC all the way to 128 on workstations.
Basically, the amount of PCIe lanes you have depends upon your processor and the motherboard chipset. There are many ways you can determine this number, the easiest is to consult the specifications of the product.
Knowing how many PCIe lanes do I have is important if you want to add a new component to any of your PCIe slots. Installing devices that occupy more PCIe lanes than available can underutilize, undercut, or worse still, render the installed components inoperable.
It is also important to note that the number of PCIe lanes your system has does not equate to PCIe lanes available for you to use. For instance, if a certain motherboard chipset, like the Intel Z490, offers 24 PCIe lanes, it does not mean all 24 PCIe lanes will be available to you in the shape of PCIe slots for you to install cards on.
Most of these lanes will be occupied by the onboard motherboard controllers and components like SATA ports, USB controller, SSD port etc.
How Many PCIe Lanes Do I Have?
- PCIe Lanes on the Motherboard Chispet
- PCIe Lanes on the CPU
This information can be found through their respective specsheet.
Also Read: What are PCIe Lanes?
1. PCIe Lanes on a Motherboard Chipset (PCH)
Let us first look at the PCIe lanes available to you from the motherboard chipset or PCH. This is a bit harder to understand as compared to PCIe lanes available from the CPU (more on that below).
Basically, 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 how many PCIe lanes a motherboard can have and how many PCIe lanes from the motherboard can be available to you for use.
For starters, you can find out the amount of PCIe lanes a certain chipset offers by consulting the manufacturers website.
For instance, the Intel Z390 has 24 PCIe lanes as per the product specifications sheet online:
Following are some of the chipsets and their corresponding PCIe lane count.
|B460||16||Mid Range /
|B560||12||Mid Range /
Again, as stated earlier, the amount of PCIe lanes here DOES NOT mean that they are available for you to occupy in the shape of PCIe slots. Many of these are occupied by the controllers and components on board the motherboard.
Example with an X570 Chipset
Let’s further see how many PCIe lanes you can have from the motherboard using the AMD X570 as an example. This is a high performance chipset so naturally has a higher number of user accessible PCIe lanes.
The above graphical representation of the AMD X570 chipset is a great way to understand the concept of how many PCIe lanes a chipset can have and how many you have available for use.
In the graphics above, we are interested in the three far right blocks only:
The first block says that the board will have 8 PCIe lanes available for use. This is generally in the form of an extra x16 slot with x8 bandwidth for dual graphics card slot.
Notice that the second and third blocks read “Pick One”. Manufacturers generally play with this to customize the upgradability of the motherboard. For instance a certain manufacturer may opt for 4 x SATA ports, another may opt for a higher number of M.2 slots (each extra M.2 slot occupies 4x PCIe lanes).
The decision is based on many factors. For instance the size of the motherboard is factor. While a full sized ATX motherboard has enough space to fit in more PCIe slots for add in cards, the same cannot be said about smaller boards like mATX or Mini ITX boards.
But this chipset, i.e the X570 offers 16 USER ACCESSIBLE PCIe lanes in total: 8 from first box, 4 from the second box and another 4 from the third box.
Also Read: PCIe 3.0 vs 2.0
CAVEAT: PCIe Lanes on a Chipset Can Be Shared
Since the amount of PCIe lanes are limited, you will often find motherboard components sharing PCIe lanes.
In this case occupying one slot can render some other ports or components inoperable. For instance, on some motherboards, occupying certain SATA ports can render an extra M.2 slot inoperable as they both share the lanes.
Similarly on other boards, occupying a certain X4 PCIe may render an M.2 slot inoperable.
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 other x1 and x4 HSIO (High Speed Input/Output) devices.
Chipset lanes are primarily responsible for motherboard’s built in systems like SATA controller, USB controller, build in sound card, modem etc.
2. PCIe Lanes on the CPU
When it comes to powering the main PCIe slots of your motherboard (i..e the primary PCIe x16 and x8 slots), CPU lanes are the primary drivers.
The amount of CPU lanes your processor can range from 16 all the way to 120 depending upon what processor you have.
Typically an average Intel Core processor can have 16 PCIe lanes whereas an AMD Ryzen processor can have 24 PCIe lanes.
Newer Intel Core series processor from the 11th gen and beyond offer 20 PCIe lanes or more.
Only the workstation grade processor can have an extraordinary amount of CPU PCIe lanes. For instance, the AMD Ryzen Threadripper Pro 3995WX has 120 CPU PCIe lanes.
You can find out this information from the manufacturer’s website.
The following table shows the amount of PCIe lanes found on popular current generations of CPUs:
|Processor||Generation||PCIe Lanes||Version Supported|
|Intel Core||11th |
|AMD Ryzen||5000 Series|
|AMD Ryzen||3000 Series (Non-G Suffix)|
|AMD Ryzen||3000 Series (G-Suffix)|
|AMD Ryzen||2000 Series|
|AMD Threadripper||3000 Series|
|AMD Threadripper |
|Intel Core X||Cascade Lake||48||V3.0|
|Intel Xeon||Cascade Lake||48||V3.0|
Purpose of CPU PCIe Lanes
The primary purpose of the CPU PCIe lanes is to power the main PCIe x16 and the secondary PC x16 (x8) slots.
Also Read: Why is Second x16 slot PCIe x8?
These are generally occupied by a graphics card. A typical graphics card requires 16 PCIe lanes to operate at optimal performance.
However, if you have two or three cards installed then the PCIe lanes and the corresponding bandwidth is divided.
For instance a typical 10th gen Intel Core processor has 16 PCIe lanes. If you have two PCIe x16 slots and you occupy both with graphics cards, then the PCIe lane count and the bandwidth will be divided equally as such: x8 / x8.
If you only have the primary x16 slot occupied (the top x16 slot), then the graphics card would operate at full x16 bandwidth.
Read More: Does it Matter Which PCIe x16 Slot I Use?
AMD Ryzen vs Intel Core CPU PCIe Lanes
AMD Ryzen Core Count (Desktop)
AMD Ryzen processors offer 24 PCIe lanes. However, not all of these are connected to the PCIe slots for you to put cards in.
Some of the lanes from a Ryzen CPU are dedicated for M.2 slots, other link with the motherboard chipset.
Here you can see how a typical Ryzen CPU is configured. On the left hand side you can see the how the PCIe lanes are configured here.
In the second box you can see that the motherboard provide 16 lanes for the graphics card. Another 4 PCIe Lanes connect with the motherboard and are thus NOT user accessible.
With the final 4 lanes, the motherboard has the choice to feature a single x4 NVMe M.2 slot, a combination of 2 x SATA Ports PLUS ONE x2 NVMe M.2 Slot, or a combination of TWO x2 NVMe M.2 slots.
Often the motherboard opt for a single x4 NVMe M.2 slot as it provides the best speed for the SSDs.
Intel Core Processors Lane Count (Desktop)
Intel Core processors upto 10th generation feature 16 PCIe lanes. They connect directly to the PCIe slots for operating graphics card(s).
The newer 11th Gen Intel Core i5, Core i7 and Core i9 for desktop, however, feature an additional 4 CPU PCIe lanes bringing the total number to 20.
So while 16 of these are taken up by a graphics, just as on the previous gen Intel Core processors, the 11th Core CPUs will still have four more from the CPU for occupying additional HSIO devices.
This is being used primarily for an additional M.2 slot.
Also Read: How Many PCIe Lanes Does M.2 Slot Use?
PCIe Slots and Their Lanes
A PCIe X1 slot only has a single lane. It is useful for devices that do not require high bandwidths such as USB cards.
You can also find x4 slots commonly on motherboards. The PCIe X4 slot, 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.
How to Occupy the PCIe Slots
If you have 16 lanes on your CPU, the motherboard can technically have a single x16 slot working at full x16 bandwidth or two x16 slots, one of which will operate at x8 mode.
As mentioned earlier, the second PCIe slot works at x8 because of the limited amount of PCIe lanes.
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 your motherboard provides 4 lanes, you may 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.
So to check how many PCIe lanes do I have, you have to consult both the specifications of your CPU as well as that of the motherboard chipset.
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 have.
Understand that PCIe lanes are limited. Even if your motherboard has a high number of expansion slots and ports in the shape of PCIe slots, SATA ports, M.2 slots etc, all of them may not be operable at the same time due to the limited nature of the lanes.
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