PCI-e X16 – Complete Guide PCI stands for Peripheral Component Interconnect, while PCIe stands for Peripheral Component Interconnect Express, the most dominant computer expansion card for over 20 years. The PCIe is the prevalent and most common expansion card because it increases its bandwidth every generation, hence, the reason for its fast connection speed on any motherboard.
PCI-E X16 is the 16-lane PCI Express slot and the largest/longest expansion slot. The slot provides the highest bandwidth and overall performance among every PC expansion slot. You can use the PCI-e x16 with graphics cards or GPUs, heavy-duty networking cards, and storage cards.
The PCI-e x16 slot offers the highest throughput rate and can be attached to expansion cards that require high bandwidth. This article provides information about PCI-e x16 and other common slots.
Devices compatible with PCI-e x16
There are three categories of devices you can use with the PCI-e slot; they include;
1. Graphics Processing Unit
Graphics cards, also known as GPUs, are the most common compatible device with the PCI-e x16 slot.
2. Heavy-Duty Networking Cards
The PCI-e x16 also works perfectly with high-end networking environments such as servers; its high bandwidth perfectly satisfies the requirement to manage multiple ethernet connections simultaneously.
3. Heavy-Duty Storage Cards
A PCI-e x16 slot can also work perfectly with heavy-weight storage setups, such as a multi-drive RAID card with many high-capacity drives.
Generally, graphics cards and PCI-e x16 are the best combination. Other PCI-e x16 combinations are always rare and task-specific.
Versions Of PCI-e X16
The table below briefly compares all PCI-e x16 generations.
| PCI-e x16 Gen 1 | PCI-e x6 Gen 2 | PCI-e x16 Gen 3 | |
| Single direction speed | 4GBps | 8GBps | 16GBps |
| Dual direction speed | 8GBps | 16GBps | 32Gbps |
| Release year | 2003 | 2007 | 2010 |
PCI-e X16 First Generation
This slot was released in 2003, and it is the pioneer PCI Express standard that launched the x16 slot with outstanding bandwidth. It was also the first slot introduced apart from the normal PCI, and it is located on the motherboard in the same space as standard PCI slots.
PCI-e X16 Second Generation
The second generation of PCI Express came into existence in 2007 with two times the speed, bandwidth, and overall performance of the first generation. After the first generation was launched, the first generation came with incredible improvements. As of 2007, non-express slots still existed solely to support older PCIs.
PCI-e X16 Third Generation.
The third generation of PCI-e x16 is the pioneer “modern” PCI Express standard, and it has the longest lifespan among other generations after being succeeded seven years after it was released(2010). During the third generation of the PCI Express, several improvements were made in the hardware space, including the popularity of SSD and the eradication of legacy ports like PCI.
Among the innovation made in the third generation that remained in the fourth generation is the NVMe M.2 slots onto the motherboard. The NVMe M.2 slots enable the combination of SSDS with PCI Express, although it only offers x4 bandwidth. However, you can use x16 and x8 to attach M.2 to your computer without the slot.
The table below briefly compares the PCI-e x16’s fourth, fifth, and sixth generations.
| PCI-e x16 Gen 4 | PCI-e x16 Gen 5 | PCI-e x16 Gen 6 | |
| Single direction speed | 32GBps | 64GBps | 128GBps |
| Double direction speed | 64GBps | 128GBps | 256GBps |
| Release year | 2017 | 2019 | 2022 |
PCI-e X16 Fourth Generation
The PCI Express fourth generation is one of the latest standards and is a common feature among motherboards produced since 2017. The PCI-e fourth generation signifies a significant change to PCI-e since the third generation was released seven years ago. It also contravenes the higher-end of NVMe and modern GPU capabilities.
Last-generation GPUs started breaking the maximum bandwidth capabilities offered by the PCI-e third generation, hence the need for the fourth-generation PCI-e x16 or a newer version to perform effectively.
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PCI-e X16 Fifth-Generation
The fifth generation of the PCI-e x16 was released in 2019 and quickly became a significant improvement to the fourth-generation motherboards. As of 2022, GPUs, such as the RTX 4090, could not handle the bandwidth offered by the fifth generation of PCI-e x16.
Until now, no graphics card can effectively manage the bandwidth the PCI-e x16 version 5.0 provides without bottleneck.
PCI-e X16 Sixth-Generation
It was released in 2021 and is the newest PCI-e standard; however, no motherboard has featured the 5.0 version yet. Anandtech predicts that the commonplace usage of PCI-e x16 won’t happen until late 2023, and consumer motherboards may not feature it until 2024.
Also, it is nearly impossible for any GPU produced in the next five years to handle the bandwidth offered by PCI-e x16 version 6.0.
Are All PCIe X16 Slots The Same?
Some differences have been listed above, but apart from that, it is essential to note that there are motherboards where PCI-e x16 slots are reduced to x8 bandwidth. In another instance, you can see a single x16 slot instead of an extra x16 slot on x8 bandwidth. Also, reductions like this are made to lower the cost of production.
All these compromises are common on budget motherboards. Carefully inspecting the body parts, you will see the differences as in the image below;
Multiple full-size and full bandwidth PCI-e x16 lanes are typically found on modern high-end motherboards. Also high-end motherboards have enough power supply and chipset to at least handle the bandwidth provided by multiple full-speed PCIe x16 slots.
Final Words
The PCI-e x16 is the largest size widely accessible for any PCIe version on consumer-grade motherboards. It offers the highest bandwidth; hence, it is used for expansion cards, such as graphics cards and storage cards that need extra bandwidth.
Frequently Asked Questions
1. How Do I Use The PCI-e Slots In My Motherboard?
If you have a single x16 card, you don’t need a high-end motherboard or processor for the expected slot support. Also, you must know that it is easy to spot the difference between an original PCI-e x16 slot and an x8 PCI-e x16 lane when you know your needs. Go for high-end motherboards if you plan to use multiple PCI-e cards.
2. Can I Use Pci-E X16 In A PCI-e X8 Slot And Vice Versa?
This is possible, but there is a catch. There is no disadvantage if you se the PCI-e x8 cards in an X16 slot. The reason is that larger slots can handle lower ones effectively without issues. However, using PCI-e x16 in an x8 slot means you won’t use all the connectors, which will reduce overall performance. Also, you won’t be able to use all the bandwidth.
3. Are There Devices That Use PCI-e X8 And X16 Cards?
PCI-e x8 and x16 cards are commonly used with graphics cards, sound cards, and storage extension cards. PCI-e x8 slots are common with storage expansion cards, while the x16 is found with modern gaming devices/graphics cards and expert-level video/image editing devices.
4. Are There Devices That Only Need The PCI-e X16 To Function Effectively?
The PCI-e x16 is mainly used with GPUs; however, there are other devices that need this slot for better performance. They include; NVMe SSDs, RAID controllers, and network adapters.
5. Is PCI-e x16 SSDs Available?
PCI-e and NVMe SSDs do not need the x16 bandwidth. NVMe SSDs only need PCI-e x4 bandwidth with dedicated M.2 NVMe lanes. Note, most PCI-e SSDs that were produced as actual cards have been replaced by NVMe drives. Even Intel’s specialized Optane SSDs, which maintain a card-like form, utilize PCIe x4 rather than x16.