How Do I Know If I Have PCIe X8 Or X16?

A PCIe slot is one of the most important slots for people that like to build their own PCs. It upgrades the system’s features and takes additional settings that do not come pre-installed when you buy your computer. A PCIe slot is present at its designated place on the motherboard and directly connects to higher specifications such as better graphics processors and additional memory units.

Each motherboard comes with at least 2 such PCIe slots, and depending on the model you purchase, you can have a lot more such slots. However, all PCIe slots are not the same size. They come in different formats as well. So how will you identify a PCIe slot and check its size and compatibility with your device? Read on to find out.

1x 4x X8 Or X16
x1 x4 x8 or x16 card
4x 8x
PCIe (PCI Express Connectors) x1 x4 x8 and x16

What is a PCIe or a PCI express?

The PCIe is the short form abbreviation of “the Peripheral component interconnect express”. This is a standardized slot to interface all motherboard components for additional capabilities and specifications of graphics, memory, and storage as well.

Firstly, it is called the “peripheral component interconnect” to signify its design capabilities in handling point–to–point connections for all non–core components of your PC. The term “express” was added later to denote the shift from the previous designs to show the added better features on the new and latest universally accepted standardized versions of these slots.

PCIe Slots and PCIe Cards

The peripheral component interconnects express slot is the point of contact on your motherboard for you to place your “peripheral components” and connect them to your PC.

The peripheral component interconnects cards, more commonly known as expansion cards, are simply the additional components you wish to connect to your PC. These are graphic cards, solid-state drives (SSDs), hard disk drives (HDDs), CPUs, etc.

You are supposed to place your PCIe card onto the PCIe slot on your motherboard and connect the two in a way similar to just building lego sets. The look and feel of these connections are very much similar to building blocks (not even kidding).

Some Standard PCIe Sizes

While the underlying technology is the same and the working protocols of the PCIe are standardized around the world, there are some differences in the sizes of the PCIe slots and PCIe cards. The most common slots are as follows:

  • PCIe x1
  • PCIe x4
  • PCIe x8
  • PCIe x16

Each of these sizes corresponds to the number of data lines present on the PCIe slot or the PCIe card. The number of data lines determines how data is exchanged between the motherboard and the peripheral devices.

Typically, the higher the data lines present, the faster your hardware can be expected to perform. For any two devices with the exact same specifications, the one with the higher data lines would normally work much faster than its previous sizes. Sometimes, the data lines are also more commonly called lanes. In the simplest of terms, more data lines mean more speed between your computer and your peripheral device. This does not mean the only difference between a PCIe x8 and a PCIe x16 is the speed. Although not common, there are usually several other specs and requirements involved that can make your PCIe slot incompatible with your PCIe card. It is always advisable to check your hardware requirements and purchase your devices.

How PCIe Generations Can Impact Speed

So far, the transfer rates of different generations of PCIe slots and cards have doubled with each new generation. However, this approach was abandoned from the generation 3 series to increase the transfer rates in the multiples of 8 since this is more feasible. Newer generations offer double the bandwidth that their directly previous ones. You can use the maximum of your hardware if you connect your ports and slots of the same generation and size.

The PCIe generation 4. 0 offers a bandwidth capacity of up to 64 Giga Bytes per second and a transfer rate of 16 Giga Transfers per second. Newer versions of the PCIe are always showing up and creating better features for the people that buy them. This translates to better and faster hardware capabilities for the general public.

The Difference Between the PCIe X8 And The PCIe X16

It is fairly easy to tell if you have the PCIe x8 or the PCIe x16. For one thing, the PCIe x8 is half the size of its counterpart and only has 8 data lines compared to the 16 data line of the PCIe x16 slot or card. Simply counting the number of data lines on your motherboard or the peripheral device would give you a conclusive idea of which PCIe you are having. However, the version you are using is a bit tricky since they are not much different visually. Check the specifications on the hardware and see if you have compatible equipment.

How To Overcome The Differences Between The PCIe X8 And PCIe X16

Even if you do have different sizes of PCIe slots and devices, you need not worry, as you can use an extension cable specifically designed for this purpose. With such cables, you can easily connect the PCIe x8 device to the PCIe x16 slot and vice versa. The performance would not be optimal since they are different versions and sizes, but it would be a doable compromise for your uses.


How do I know if my PCIe is 16x?

Look at the slot

Remove the case or side panel for your PC to locate the motherboard. You’ll see something that resembles the one in the image below. If you find a port that’s the same as the highlighted one, then your motherboard is equipped with a PCIe x16 slot.

PCIe x16

How do I know what PCI slot I have?

Click on the “Motherboard” link located in the navigation pane. The PCI slots on your PC will display under the PCI Data group. The specific type of PCI slot is listed next to “Slot Type” with each PCI entry. For example, “Slot Type – PCI-Express” indicates that your computer uses PCI-Express slots.

Can I use PCIe x8 in the PCIe x16 slot?

Yes. A larger PCI express slot fits all smaller PCI Express cards. That means you can plug an x1, x2, x4, or x8 card into an x16 slot, an x4 card into an x8 slot, and so on.

How can you tell the difference between PCI and PCIe?

The main difference between PCI and PCI Express is that the PCI is a parallel interface while PCI Express is a serial interface. PCI is a bus that allows connecting devices inside the computer to extend its capabilities. The original PCI standard provides a data transferring rate of 133 Mbps.

What’s PCIe x16?

PCIe x16 is a slot on a motherboard that has 16 data links known as PCIe lanes. This is a slot with the highest throughput rate and can be occupied with expansion cards that have a very high bandwidth requirement such as graphics cards.

What is the difference between PCIe x1 and x16?

In general, one -x16 card, has 16 transmit and 16 receive pairs/lines. One -x1 card, has 1 transmit and 1 receive pair/line. Theoretically, a -x16 card has to be 16 times faster than one -x1 card. PCI Express interface allows the work of a card, using the smaller number of transmit/receive pairs.

Can I plug PCIe x1 into PCIe x16?

The short answer is yes. You can plug a PCIe x1 card into the larger PCIe x16 slot. A PCIe x1 card can be plugged into any larger PCIe slot and it will work just fine.

Do laptops have PCIe slots?

No laptops have pci or pcie. They do however have mpcie but that is not for gpus and is usually occupied by the wireless card. Laptop’s gpu slot is mxm and only high end gaming laptops will have them.

Do all motherboards have PCIe slots?

Every desktop PC motherboard has a number of PCIe slots you can use to add GPUs (aka video cards aka graphics cards), RAID cards, Wi-Fi cards or SSD (solid-state drive) add-on cards. The types of PCIe slots available in your PC will depend on the motherboard you buy.

What is PCIe x8 used for?

This slot is used for devices like an NVMe M. 2 SSD expansion slot or 4k video capture card, that require a higher bandwidth than an x1 slot an offer. x16(x8): These are found on premium motherboards for dual graphics card builds.

Can you put a PCIe x4 in a x8 slot?

You can use PCIe cards of a lower lane width (e.g., x2, x4, or x8) in a higher lane width slot (e.g., x16). PCI-Express will negotiate how many lanes will be used, and your card will work at its full speed, assuming the PCIe slot has the same or higher PCIe version.

What can you plug into PCIe x16?

x16 – This slot has 16 PCIe lanes – Used for cards that require a high bandwidth like graphics cards; these are the largest slots on the motherboard….

  • Graphics Cards (GPUs)
  • Sound Cards.
  • Ethernet Network Cards.
  • WiFi + Bluetooth Network Cards.
  • Video Capture Cards – AKA Game Capture Card.

Do graphics cards use PCI or PCIe?

Graphics cards connect to computers through three different connection types: PCI, AGP, and PCIe. PCI and PCIe interfaces are intended to support a wide range of devices, while AGP is solely intended for graphics cards.

Is PCIe compatible with PCI?

PCIe (PCI Express®) is the more recently introduced standard for connecting devices to computers. It’s software-compatible with PCI but has higher potential bandwidth and greater flexibility than PCI. The PCIe specification is also maintained by the PCI-SIG.

What does a PCIe slot look like?

PCI Express slot is basically rectangular that protrudes out of the motherboard and has many terminals on either side. PCI Express slots look different depending on their sizes, x1, x4, x8, and x16.

Can you put a WiFi card in PCIe x16?

It should be noted, however, that while ideally an x1 slot should be used, you CAN fit the Wireless card in other larger slots i.e the X4, X8, or even the X16. But, you should also note that installing the WiFi card in a larger PCIe slot will not give any kind of performance boost to it.

Does it matter which PCIe slot I use for the WiFi card?

Yes, the PCIe slot that you use for your expansion card does matter. This is because different PCIe slots have different throughput rates (speed) and lane widths.

Are all PCIe x16 slots the same?

The PCIe x16 slot is the fastest in any generation as it has the most PCIe lanes available and this results in a higher data throughput (speed in layman’s terms). This slot is ideal for large and power hungry cards like a graphics card. However, not all x16 slots are created equally.

Can PCIe x4 fit in PCIe x16?

Simply put, a PCIe x4 card CAN fit in a PCIe x16 slot. The main reason this is possible lies within the fact that PCIe standard is cross-compatible as well as backward compatible. Meaning, PCIe devices can work in different slots as long as they are provided the required PCIe lanes.

How do I install a PCI slot on my motherboard?

You can add more PCIe Slots to your computer using a PCIe splitter. You do need to have a free PCIe expansion slot on your motherboard so that you can plug in a PCIe splitter, aka riser, which then fans out to multiple external PCIe slots.

Can you put PCIe 4x in a 16x slot?

PCIe boards can fit into slots designed for their lane configuration or higher. Plugging a x4 PCIe into an x16 slot (up-plugging) is acceptable. The opposite (down-plugging) is not physically supported.

Can you put a mini PCIe into a PCIe slot?

A PCI Express Mini Card can not be put directly into a non-mini PCIe slot. I just took a PCI Express Mini Card and a motherboard with an PCIe slot. It is quite obvious that the two are not physically compatible, the physical dimensions in the connectors are simply different.

Will a PCIe 2.0 work in a PCIe x16?

Typically they will all be PCI Express, but for a graphics card, you need a PCI Express x16 slot. There are three versions of this slot, but they’re backwards compatible, so a modern PCI Express 3.0 graphics card will work in a motherboard with a PCI Express x16 2.0 slot. This motherboard has two PCI Express x16 slots.

Will a PCIe 3.0 x16 card work in a PCIe 1.0 x16 slot?

PCIe 3.0 cards are backwards compatible with the 1.0 and the 2.0 slots, but you won’t be able to enjoy the full extent of your new PCIE card.

How do I know if my laptop has mini PCIe?

The best way is to pop off the access panel and see. Just to note, they will be mini PCI-e if anything, usually you’ll have one for the WiFI/Bluetooth adapter.

How do I know if my laptop has a graphics card slot?

First, go to the START menu and then type “dxdiag” (without quotations), then click the Display tab and it should say what kind of graphics your computer has.

How do I know if my motherboard supports PCIe 4?

You have to enter the device you are using and the specifications would appear. Once the specifications are available, you would know the PCI express slot version that is installed on your motherboard. It is generally available under the ‘Expansion slots’ specification in the manufacturer’s website.

How do I enable the PCI Express slot in BIOS?

Enabling or disabling PCIe Slot Network Boot

  1. From the System Utilities screen, select System Configuration > BIOS/Platform Configuration (RBSU) > Network Options > Network Boot Options > PCIe Slot Network Boot.
  2. Select a PCIe slot entry.
  3. Select a setting.
  4. Save your changes.

What can I put in a PCIe X8 slot?

Yes, you can put a PCIe X16 card in an X8 slot. Electrically, there is no difference between the two as they both receive the same 75 W of power from the motherboard. The only difference between the two is the data bandwdth, a PCIe gen 3 X16 slot supports ~16 GB/s, while a X8 slot supports ~8 GB/s.

What PCIe cards are there?

There are 5 common types of PCIe slots and cards: x1, x2, x4, x8 and x16. The numbers represent the number of lanes on the card or slot. Just like the lanes on a road, these lanes are paths for data to travel on.

What is the difference between PCIe x4 and PCIe x16?

The short answer is:

‘PCIe x4’ connections have four data lanes‘PCIe x8’ connections have eight data lanes‘PCIe x16’ connections have sixteen data lanes.

What devices use PCIe?

Peripheral devices that use PCIe for data transfer include graphics adapter cards, network interface cards (NICs), storage accelerator devices, and other high-performance peripherals. With PCIe, data is transferred over two signal pairs: two wires for transmitting and two wires for receiving.


The fundamental difference between the PCIe x8 and PCIe x16 is that the PCIe x16 has twice the data lines as the PCIe x8. This gives you double the transfer speed and also a much higher bandwidth capability between your motherboard and your peripheral device. You have to make sure the sizes on your slots and devices are the same. If they are not, you will have to use an extension cable to make your slots and cards compatible.

Andy Avery

I really enjoy helping people with their tech problems to make life easier, ​and that’s what I’ve been doing professionally for the past decade.

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