The PCIe connection, or PCI Express, is a type of bus that has prevailed today due to its magnificent features. Modern motherboards have adopted it, leaving behind the old AGP for graphics cards, as well as including this type of interface also to improve the speed of other devices, such as PCIe SSDs.

However, there is not only one type of PCIe, as there was also with AGP, but there are several types and versions, all with notable differences and for slightly different purposes. In this guide, you will learn everything you need to know about these expansion slots on your motherboard.

What Is Pcie Or Pci Express?

You should not confuse PCIe or PCI Express with PCI-X, which is an extension of PCI buses and has clear disadvantages compared to PCIe. It is something that generates a lot of confusion, and it is easy to fall into the idea that they are synonymous terms.

Both are buses, but PCI-X, or PCI eXtended, is totally incompatible with PCIe, apart from the fact that it works at 64-bit in parallel, while PCIe slots are serial points, among other details.

PCIe is a serial data communication that was developed in 2004 primarily by Intel, in collaboration with other companies despite being a proprietary technology, it was later released to become a standard. The idea was to find a successor to the AGP, which had already reached its peak.

This uses full-duplex lanes (it can send and receive at the same time), and depending on the PCIe version, the amount of data transferred per second can vary, as well as its number depending on the type of slot. For example, you can find: from those that use a single PCIe x1 lane, to those that have sixteen lanes or x16.

As for its uses, although it is mainly used by GPUs or graphics cards, it is also currently used for SSDs, as I mentioned earlier, and to connect other types of expansion cards (sound, capture cards...) and devices.

PCIe Lanes

One thing to keep in mind is the number of PCIe lanes. If you have looked at your motherboard, as was the case with AGP (x4, x8), not all slots are the same size. The longest is x16 or sixteen lanes, and therefore the most powerful and occupied by graphics cards.

Other less demanding devices can be connected to shorter slots or fewer lanes. There are configurations of:

• 1 lane (x1): it is the smallest slot of all, and is widely used by some expansion cards that are not very demanding in terms of data transfer.
• 2 lanes (x2): this other slot is usually widely used by SSD hard drives. And it is also small and different from the rest.
• 4 lanes (x4) - Not very common, only used by some rare expansion cards. In fact, many motherboards lack them and simply add more x1 or x16 slots that are more used.
• 8 lanes (x8): As with the previous one, it is not used very often, so it may be absent on many boards. It's usually on certain high-end (HEDT) motherboards, especially for servers.
• 16 lanes (x16): yes, it is very popular since it is the one used by graphics cards as it is the most powerful. It has sixteen lanes for much faster transfers. There are usually one or two, in case you can install more than one GPU.

Versions

In addition to the number of lanes, there are also a number of versions. The PCIe is not static, but is in constant development, so new improved versions are released from time to time. Although these cannot be distinguished with the naked eye looking at the slot, as was the case with the rails, but will depend on the hardware support. For example:

• PCIe 1.0: the first version allowed 8b/10b encoding, reached a transfer speed of 2.5 GT/s (gigs transferred per second), and reached up to 2Gb/s per lane (250MB/s). Therefore, in the x16 configuration, it would go up to 32Gb/s or 4GB/s.
• PCIe 2.0 - The next release used the same type of encoding, but went as fast as 5 GT/s throughputs. Each lane could reach 4Gb/s (500MB/s) and x16 reached 64Gb/s or 8GB/s. That is, it doubled the speeds of the previous one.
• PCIe 3.0 - Switched to 128b/130b encoding, achieving 8GT/s transfers. Each lane could carry up to 7.9Gb/s (984MB/s) and with the 16-lane configuration, 126Gb/s was reached, that is, 15.8GB/s.
• PCIe 4.0 - This is a newer version still in use. The values of the previous one are doubled, with 16 GT/s, and each lane supports 15.8 Gb/s (1969.2MB/s), which reaches 252.1Gb/s (31.5GB/s) in maximum configurations of x16. ).
• PCIe 5.0: many computers are already appearing that support this new standard that also doubles the previous figures, that is, 32 GT/s, 31.6 Gb/s (3938.4 MB/s), and 504 Gb/s (63GB /s) respectively.
• PCIe 6.0: When version 5.0 has just appeared and 4.0 is still used, a future improvement, the sixth version, is already planned. Again it would double the previous one, with 64 GT/s, lanes up to 64Gb/s (7877 MB/s), and x16 configurations up to 1008 Gb/s (126GB/s).