What PCIe Slot Should I Use? – Learn Here

If anything to do with PCIe slots and their use gets you confused then you are in the right place. We’ll take a closer look at what PCIe slot should be used with which devices and get you acquainted with the subject.

For starters, PCIe slots let you connect fast components to your motherboard, allowing you not only to extend your computer’s feature-set but also to let you upgrade and customize your PC’s performance over time.

As time goes by, more and more people are getting a hang of their motherboards and as we continue to be savvier, we should know what components to use where.

So, what PCIe slot should I use? The short answer is that it depends. Firstly it depends upon the device you want to install. Secondly, the slots come in different configurations as well as generations. Therefore, you should use the correct generation slot-device pair and try and match up the size as well.

PCIe Configurations

Before we rush into the details about PCIe slot usage, let’s get some few things out of the ways so that we’re on the same page.

PCIe slots come in different configurations on a motherboard, giving users the ability to use any number of peripherals that are supported.

These configurations are named X1, X4, X8, and X16, and the naming corresponds to the number of lanes available. How so? Well, the number after the X refers to the number of lanes for the given slot. So, X1 has just one lane and X16 has 16 lanes.

With different configurations, some confusion can arise as to what slot should be used for which device or how many devices can be used here.

PCIe Slots on a motherboard
Many motherboards have a combination of different PCIe Slots. Source: tweaktown.com

Also Read: What PCIe Slot do I Have?

What PCIe Slot Should I Use?

If you take a look at your motherboard, you will notice that there are several PCIe slots available for your use. So making use of them will boil down to how many slots you have, and which configuration they are in.

Slot configuration matters a lot because while PCIe slots are cross-compatible, performance hits may occur when using larger devices on smaller slots. So, if you plug an X16 device into an X4 slot and it fits, the setup will work at the maximum speed of the X4 device. Thus, you lose performance.

Besides slot configuration, another thing you need to look out for is the generation of the PCIe device you are using.

Different generations have different lane speeds. If you plug an X1 PCIe 3.0 device into an X1 PCIe 2.0 slot, the setup will perform at the slower speed of the X1 PCIe 2.0 slot. So, if the device needs faster speed, it won’t get it.

Also Read: PCIe 3.0 vs 2.0

When all is said and done, the slot you use will depend on the device you have. Here are some guidelines about when to use which slot.

Also Read: 7 Reasons When to Upgrade Motherboard

When to Use the PCIe X1 Slot

This slot has only one PCIe lane. As a result, it’s meant for devices that do not require a lot of bandwidth transmitted over a line.

You should use this slot if you have a PCIe X1 device.

The reason is that the X1 device was meant for this slot and will definitely fit and work perfectly.

So, if you have a TV tuner card, go ahead and plug it in. The card will make use of the single lane and provide you with TV access on your PC.

Additionally, some port expansion cards work well with the PCIe X1 slot and they add more I/O like extra USB ports, etc.

Lastly, sound cards. These help with providing better audio playback on your machine. And the best part is that they do not require a lot of bandwidth to work.

If you have any of the devices mentioned above, then you should use your PCIe X1 slot. While they are fast, they do not require a lot of bandwidth which is great.

What PCIe Slot Should I use?
When you have multiple PCIe slots, its best to choose the one that best supports your device. Source: tomshardware.com

When to Use the PCIe X4 Slot

The X4 slot is larger than the X1 slot and hence it carries more bandwidth since it equally has more lanes, four to be exact.

The slot is great for devices that have moderate needs for bandwidth but still lie on the lower side.

When should you use this slot? You can do a lot with it. First, you can fit all the devices for the PCIe X1 slot on a PCIe X4 slot when you do not have any X1 slots available.

Furthermore, if you have a network adapter like the Asus XG-C100C, you can use the PCIe X4 slot to add 10 Gigabit network support to your computer. This would be great for online gamers and streamers.

You can also use the PCIe X4 slot with an SSD adapter card to add faster storage devices to your computer. This can help by improving PC booting times as well as reduce delays with starting programs.

Also Read: Which PCIe Slot for Wireless Card?

When to Use the PCIe X8 Slot

With an X8 slot, you get double the bandwidth of the X4 slot. This means that you get much more data being transferred with every cycle and as such, the slot is meant for really fast devices.

You can use this slot if you have some Network Interface cards that come in the X8 configuration. This is of course for requirements that are above those needed by the X4 cards. You can have multiple gigabit Ethernet ports on a card like this.

Also, some graphics cards can be plugged into the X8 slot.

When to Use the PCIe X16 Slot

The PCIe X16 slot is the one most people use for some of their most demanding cards. A good example is a high-end graphics card. These require a high-bandwidth connection to the CPU and the PCIe X16 slot can provide this.

Besides the high-end graphics card, you can also use this slot with an NVMe to PCIe adapter that comes in the X16 configuration like this one from Siig.

PCIe X16 slots offer the best performance and can be used with any regular-sized PCIe device without any issues.

PCIe devices and their connectors.
These are some of the most common PCIe connectors you will see in PCIe devices. Source: howtogeek.com

Compatibility Issues

With the PCIe standard, compatibility issues are not so widespread. You can use any device with any slot as long as it fits.

The best way to go about this is to use the slot that was meant for the device or a larger one. If these are not available then your next option can be to use a smaller fitting slot.

Ensure that you’re using the correct slot for the best performance and ensure that you don’t mix PCIe version slots and devices unless it’s completely necessary as this can cause potential bottlenecks.


When it comes down to what PCIe slot should I use, having a good understanding of their slots and their functionality can significantly improve your overall experience with your setup!

Here’s the thing, because there are multiple PCIe configurations, many users can be tempted to use whichever device wherever they want. However, ensure you follow the guidelines, some of which are covered here, for the best overall performance.

While choosing which PCIe slot to use, ensure that you have read the manual to see that the slot has the necessary specs to support the peripheral device you want to install.

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