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How Many PCI Express Lanes Do I Need?

It is important to get things right the first time when dealing with computer components. If you have been wondering, how many PCI Express Lanes do I need, you are in the right place.

There are PCIe lanes on your motherboard and the processor. Ultimately, the PCIe lanes on the CPU will determine the maximum number of lanes you can use. But, the actual number of PCIe lanes you need depends on the expansion cards you need to install.

The performance of a computer depends on a lot of aspects which include the kind of hardware attached to it as well as their performance. PCIe offers a high-speed connection of different devices to the CPU.

The connection happens over PCIe lanes that are made of a pair of wires. More of these lanes mean support for more components.

How Many PCI Express Lanes Do I Need?

The actual number of PCIe lanes you need will vary a lot. In one way, they will be determined by the kinds of hardware you want to install.

PCIe expansion cards have varying needs in terms of bandwidth. To cater to these needs, the slots are configured for PCIe X1, X4, X8, and X16; and these have 1, 4 8, and 16 PCIe lanes respectively.

Some devices require more data lanes to function, like graphics cards that perform at their best with 16 lanes.

Also Read: How Many PCIe Lanes Do I Have?

PCI Express Lanes on Motherboard Chipset

How Many PCI Express Lanes Do I Need
AMD X570 PCie lane architecture.

PCIe lanes are the means through which your PCIe expansion cards communicate with the rest of the system.

To do this, there must be corresponding connections on the motherboard that direct the flow of data and even power to the necessary components.

While the lanes are connected to the motherboard for communication the amount of PCIe lanes available to you are determined by the motherboard chipset as well as the processor.

A typal chipset can offer anywhere between 16 to 24 lanes depending upon the chipse you get. For instance the AMD X570 chipset has 16 PCIe lanes whereas the Intel Z490 has 24 lanes.

It should be noted that not ALL chipset lanes are available to use as many of them are connected to ports and connectors like the USB ports, video controller, network controller etc.

PCI Express Lanes on CPU

The CPU also has PCIe lanes. It is the brains of the computer and it processes various signals from different devices.

It needs to keep track of this and also needs to have a way to take in and process that data fast. This is where PCIe lanes come in.

The PCIe lanes on a CPU depend completely on the chips model. Some have more than others, and some of the silicon with higher lane counts are more expensive. But in return, you get a highly scalable device that will allow you to add numerous expansion cards.

A good example is the Ryzen Threadripper 3990X processor from AMD. It has 88 PCIe lanes which make it capable of handling several expansion cards at maximum performance.

A typical processor like the Intel Core i7-10700 processor offers 16 lanes. You can also find 24 PCIe lanes cpus like the AMD Ryzen 5 3600.

What Your Expansion Cards Need

Your PCIe expansion cards get installed into PCIe slots which run their data through PCIe lanes to the rest of the system.

Your expansion cards will play a huge role in determining how many PCI Express lanes do I need as they each have different bus requirements.

The Bare Minimum

The first 16 lanes will likely be taken up by your graphics cards. These can work just fine in the X8 slot, but newer cards push out such large amounts of data that they would require all the 16 lanes to work effectively.

The cards come as standard with an X16 slot and are necessary if you’ll be doing moderate to graphics-intensive tasks.

On some motherboards or CPUs where integrated graphics is supported, you will be able to run your computer without having a graphics card.

High-Speed Devices

m.2 expansion card
A typical M.2 NVMe High Speed expansion card utilizes 4 PCIe lanes

Other PCIe cards will use anywhere from the X1 to the X8 slots. As such, for each device used, you will need to determine the slot you will be installing it on to figure out the number of lanes you will need.

Other lanes will be used by various other components of the motherboard. These should be factored in as well because the total number of lanes available is fixed – and is finite.

Also Read:

Lanes Are Finite

Chances are you know the number of PCIe lanes on a motherboard is limited, which is why you want to know how many PCI Express lanes do I need.

As stated, this depends on the devices you need to have installed on your computer. However, there is a catch.

Maximum Usable Lanes

The maximum number of lanes you can use on your computer depends on the total number of lanes that the CPU has available.

If you install more devices than the CPU can handle with its available lanes, some slots will have to share lanes. This is not always such a bad thing though.

Sharing Lanes

The motherboard’s documentation has some information about how it handles situations where more devices are installed which surpass the maximum supported lanes of the CPU.

The bandwidth of certain slots will be reduced so that the CPU can accommodate all the traffic from the different devices.

Thus, the number of lanes you need should correspond to the maximum number of lanes your CPU supports. However, if this feels limiting, you can surpass the value, at the expense of some underperforming devices.

Motherboard specifications have many details and caveats whereby they specify how the PCIe lanes are distributed. In many cases, using a certain PCIe slot may render another inoperable as they share the lanes.

So for instance a motherboard may have an M.2 NVMe Slot sharing PCIe lanes with a PCIe X4 slot. Hence occupying either one would render the other useless.

What are PCIe Lanes?

Conclusion

PCIe lanes are limited. As such, knowing how many PCI Express lanes do I need can come in handy when making a purchasing decision or deciding on cards to install.

Different cards use different numbers of lanes and the sweet spot is finding a CPU that can accommodate that number.

If you need more devices, you can install them and get to share bandwidth between some PCIe slots.

Another alternative is to just get a CPU that has enough lanes to cater to the amount you need. You may pay more, but get good performance and hardware in return.

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