Basically, a PCIe x1 slot is used to plug in low demanding PCIe expansion cards that do not have a very high throughput (transfer rate) such as Network Adapters, Port Expansion Cards, Sound Cards and Certain Riser Cards.
PCIe x1 slot offers only one PCIe lane and thus has the lowest throughput (speed in layman’s terms) of the PCIe slots out there (depending on the PCIe version it conforms to).
If you’re someone who likes to get their hands dirty and build a custom PC, there are a few things you’ll need to know in order to use the available PCIe slots effectively.
There are several sizes of PCIe slots available, each with their specifications and purpose, but here we will particularly look at what are PCIe x1 slots used for by looking at the typical devices that fit into this slot.
Before we get into the details, lets us refresh what PCIe Slots, PCIe Lanes and PCIe version is and how they can affect the transfer speed and the overall build of your system.
What are PCIe Slots?
PCIe stands for Peripheral Component Interconnect Express. It is a standard that was created to allow the connection of high-speed devices to the motherboard.
PCIe slots are the interfaces through which the PCIe devices are connected to a motherboard. The slots come in a variety of sizes with x1 being the smallest one available.
Most motherboard have a variety of PCIe slots. Almost all motherboards have the large x16 slots. x4 and x1 slots are also very common.
- What Does a PCIe Express Slot Look Like?
- How To Check How Many PCIe Slots Do I Have?
- 10 Things That Can Be Plugged in PCIe Slots?
What are PCIe Lanes?
PCIe lanes are basically highways that connect the PCIe slots and the attached expansion cards to the CPU.
The more lanes a slot has, the higher would be the throughput rate (speed) of the slot. So an x4 slot has four times the speed of an x1 slot.
On commercial motherboards, a PCIe slot can have a maximum of 16 lanes. x16 slots are hence the largest and they can accommodate very demanding cards that generate a lot of data like graphics cards.
Now the thing about PCIe lanes is that they are limited in number. A typical PC has a total of 20-24 PCIe lanes. 16 of these are generally occupied by the graphics cards. The rest of the four lanes can either be distributed on a single x4 slot or four x1 slots depending upon how the motherboard is designed.
While this site has comprehensive resources on PCIe lanes that you can check out, for the purpose of this article, it is sufficient to know that an x1 slot only has a single PCIe lane and is hence suitable only for low demanding PCIe expansion cards.
PCIe Version and Speeds
The PCIe version of the slot has a tremendous impact on the throughput rate of the slot as well as the corresponding devices that attach to them.
Each new PCIe version doubles the per lane transfer speed compared to the previous generation.
Table: We are currently on Gen 4
Therefore, not all PCIe x1 slots are the same. The throughput of the PCIe x1 slot depends on the PCIe generation.
The most common PCIe generation at the moment is the PCIe Gen 3. The Gen 3 x1 slot has a throughput of about 1 GB/s, as can be seen in the table above.
Currently, the 4th Gen PCIe has started gaining momentum and will become widespread. The Gen 4 x1 slot has a throughput rate of roughly 2 GB/s.
To learn more about PCIe generation and there impact we recommend reading this article:
So What are PCIe x1 Slots Used For?
Despite being the smallest slot compared to the rest of the PCIe slots, the x1 configuration still offers high-speed connections between PCIe devices and the motherboard.
These are used for add in / expansion cards that have a low bandwidth requirement. The following are some of the cards that use the PCIe x1 slot.
- Sound Card
- SATA Expansion Card
- USB Port Expansion
- Network Cards
- TV Tuner Cards
- Video Capture Cards
- PCIe Riser Cards
1. Sound Card
Most motherboards come with built-in audio chipset that works just fine for many users. However, for audiophiles, dedicated sound cards can be used to get a better and a more accurate sound reproduction.
Since they do not generate a lot of data and have a low bandwidth requirement, a sound card can be plugged to an x1 slot.
Not only do sound cards provide better quality sound, they also add more ports and have better shielding against electromagnetic interference.
Again, while these are not quite essential for most users, they can come in handy by audiophiles.
2. SATA Expansion Card
The primary method of attaching hard drives to your PC is through SATA ports. If you have a limited amount of SATA ports or if you have a large storage requirement, you can get yourself an x1 SATA expansion card.
These are ideal for NAS systems.
3. USB Port Expansion
For some users, the number of USB ports that come with the system may not be enough to fit their needs.
For this reason, a good use case for the x1 slot is to get a USB expansion card.
4. Network Cards – WiFi and 1G Ethernet
There are two types of PCIe based network cards you can install to x1 slots:
- PCIe WiFi Cards
- 1G PCEe Ethernet Cards
An Ethernet card is often not needed as almost all motherboards come with one already built-in.
On the other hand, if you want to add WiFi connectivity to your desktop, then PCIe WiFi Card is one of the ways.
All wireless network cards, including those conforming to the newer WiFi 6 protocol, and all 1G Ethernet network adapters work with an x1 slot. The more powerful 10G Ethernet Cards require an x4 slot however.
5. TV Card
A TV card is a device that will let you receive TV signals directly on your computer.
With some cards, you can record your TV shows directly off the cable and watch them later. Essentially TV Tuner cards allow your computer to work as a TV.
6. Video Capture Cards
A video capture card takes video signals and converts them into digital data that can be stored on your computer. These videos can be then edited and streamed.
These cards take data from sources like a TV, a camera or even a gaming console. For this reason, they are very popular among gamers and streamers.
A typical FHD video capture requires an x1 slot.
More powerful 4k capture cards require larger x4 slot due to a higher bandwidth requirement (4k generates more data).
7. PCIe Riser Cards
PCIe riser cards, aka splitters, are a way to increase the number of PCIe slots your motherboard has.
Make not mistake, though, increasing the PCIe slots does not increase the amount of PCIe lanes you have. In addition to that, the split slots can only have a combined maximum throughput of the host slot.
Meaning if an x1 slot splits into four x1 slots, this will not increase the original throughput to four times the x1 lane.
We have an in-depth resource on this topic: How to Add More PCIe slots?
Now that you have a better understanding of what are PCIe x1 slots used for, you should be able to make a more efficient builds for your PC.
Knowing which slot to utilize and when is very important to save the slots as well as the precious PCIe lane counts your system has.
For instance, it would be unwise to fit an x1 card into an x4 slot. Although the x1 card will work in an x4 slot, you will have wasted the potential of the larger slot which could be used for more demanding cards.
While the x1 slot is the smallest, it is crucial for things like network cards, video cards, and sound cards.
We have plenty of topics and resources here on PCIe in case if you want to learn more.