PC Gear Lab

Can PCIe x1 fit in x4? – Learn Here

One way or another, many users have found themselves in situations where they need to fit their cards into a slot that is not available on their motherboards.

It happens very frequently and when you have an X1 card and no X1 slots, it may get you confused as to whether any of the larger slots can be good for your card.

If you’re here then you have this question in mind too; can PCIe X1 fit in X4. It is a simple question, and possibly the answer can be simple too. But to alleviate any doubt, we will go a little deeper into the subject to see just how exactly this happens and why it works.

Just to clarify and put it in simple, Yes, a PCIe X1 card CAN fit inside a PCIe X4 slot and it’ll work. We’ll look at this in more detail as we continue.

Let’s Get Familiar

No doubt you already know a lot about the PCIe standard. For those who are not yet familiar with the subject, PCIe (Peripheral Component Interconnect Express) is a standard that was developed to help with the connection of high-speed devices to motherboards.

PCIe X1 and X4 are two separate implementations of this standard and they have existed through multiple versions of the standard.

The number after the X refers to the total lanes that the slot has. So, an X4 slot has four lanes while an X1 slot will only have a single lane.

Since lane speeds are the same in each generation, having more lanes will mean more total bandwidth.

PCIe X1 Slot and Device
A PCIe X1 Device And it’s corresponding PCIe X1 Slot. Other Slot sizes are also shown. Source: tomshardware.com

Also Read: What are PCIe X1 Slots Used For

PCIe Lanes

Your PC has a limited amount of PCIe lanes as dictated by your processor and your motherboard chipset.

An average commercial processor gives about 16 PCIe lanes and an average motherboard gives about 4.

Managing the PCIe lanes and the slots is the key element in building a customized PC.

Also Read: Can PCIe X4 Fit in X16?

Can PCIe X1 Fit in X4?

Now that we’re acquainted with the two implementations that we’ll be discussing, it’s time to answer your question in detail.

Basically, the rule is that a small PCIe device can work on any larger slot as long as it fits, simple.

With PCIe devices and slots, the standard requires the highest degree of cross-compatibility. This makes sense because PCIe devices come from many different manufacturers and each performs different roles.

As such, the interface that connects them all needs to have high tolerances for a lot of differences.

One such difference is the number of lanes that you have on your device.

If you’d like to know if your device can fit in a certain slot, you will need to consider two things. The number of lanes that the device needs as well as the number of lanes that the slot has.

Also Read: What is a Motherboard?


In our case, we have a PCIe X1 card which, as we have seen, has just one lane. The PCIe X4 slot, on the other hand, has 4 lanes.

When you decide to pair the two, the card will end up using just the one lane it needs from the slot, leaving the other three unused.

This is not so bad since you don’t end up losing limited amount lanes that your PC has.

A motherboard has a finite number of lanes and for users who have many PCIe devices to connect, plugging an X1 card into an X4 slot should be avoided unless you do not have any X1 card slot available at all.

Additionally, because the slot is much larger than the card, you will need to ensure that you have properly secured the card to avoid any potential accidents. This is something you will always need to consider even when using the same size slot and card.

Fitting an X1 card into an X4 slot is allowed and supported. You can even do the same with an X8 or even an X16 slot but there’s usually no benefit to doing so as we’ll see shortly.

The only issue is that where a larger X4 slot would have come in handy when installing a larger expansion card, now when you have installed a smaller X1 card one on it, you have reduced its potential.

Now that we have seen that the configuration is supported by the size factor, let’s see whether you will be enjoying any benefits if you opt to connect the X1 card in the X4 slot.

Can PCIe x1 fit in x4
A PCIe X1 Device has the smallest connector. This lets you use it in larger slots fit for X4, X8, and X16 devices. Source: howtogeek.com


As mentioned earlier, the main difference between an X1 and an X4 configuration is the bandwidth that the configuration supports.

With four lanes, the X4 slot can carry quadruple the bandwidth that the X1 slot can. This makes the X4 slot the better candidate for large data transfers.

The question here is, will plugging your X1 card into the X4 slot make it run faster?

The short answer is no.

The card will not necessarily work any faster than it would in the X1 slot and the reason is that the maximum bandwidth use for the card is limited to the number of lanes that it can connect to.

The X1 card can only connect to one lane physically and as such it will only use the one lane. Therefore, it won’t be faster in the X4 slot.

But there are cases where the card can be slower! Surprised? Let me explain.

Backward Compatibility

In the PCIe standard, a link will work at the maximum speed of the slowest component. This means that if you have an X1 card in an X4 slot since the X1 card is the slowest, the speed of the connection will be limited to the speed of the X1 device.

As we mentioned, there are several versions of the PCIe standard and they are backward compatible. So you can use a PCIe 3.0 device in a PCIe 2.0 slot.

If you have a configuration that makes use of a PCIe 3.0 X1 card and a PCIe 2.0 X1 slot, you may notice a performance decrease based on a simple factor, the bandwidth of the link:

A PCIe 3.0 lane transmits data at about 1GB/s whereas a PCIe 2.0 lane does half of that, roughly 500 MB/s.

Backward compatibility is a huge plus, but when you need to use your card at its full capacity and its lanes are slower, you may opt for a larger slot with higher speeds.

Also Read: Which PCIe Slot for Wireless Card?

Points to Note

A PCIe card requires certain specs to be met for it to function optimally. Assuming your card and the slot are part of the same PCIe version, you will fulfill the card’s requirements if you use the X1 card in the X4 slot.

The card will work just fine and deliver great performance just as it would in the X1 card.

You, however, need to ensure that you’re using the correct slot because physical slot sizes alone do not tell the whole story. Larger slot sizes can operate in a configuration with fewer lanes.

You may notice on certain motherboard a full X16 slot may only be operating at X8 or X4 bandwidth at MAX. Therefore, reading the motherboard spec sheet if very important.

PCIe X1 Sound card from Creative.
You can fit a PCIe X1 sound card like the one pictured above in any PCIe slot on the motherboard, including the X4 slot. Source: creative.com


Hopefully, your question has been answered and your concerns about can PCIe X1 fit in X4 have been lifted.

The PCIe standard gives users a lot of customization options, allowing the use of different sized devices and slots together.

The X1 card will work just fine in the X4 slot, and it will work at its best speed because it isn’t limited in bandwidth.

It helps to know that you can customize your build like this because different users have different needs that can’t all be met the same way.

Regardless of what the build entails, PCIe standards are flexible.

Add comment

Your Header Sidebar area is currently empty. Hurry up and add some widgets.