The PCI Special Interest Group (PCI-SIG) aren’t messing around anymore. Earlier in May, they released the final PCIe 5.0 specification. And just weeks after that, they announced that work on PCIe 6.0 were already on the way.
PCIe 6.0 will most likely be coming out in 2021/22. And based on what PCI-SIG have shared, the I/O performances it promises seem like a bit of an overkill. In this article, we will be discussing the PCIe 6.0 standard and how that could change the PC computing and technological landscape.
But before we get to PCIe 6.0, we need to start with a little background.
PCIe 5.0 and earlier
PCI-SIG announced the completion of the PCIe 5.0 specification back in May. The Chairman and President of the group, Al Yanes, shared how he believed this would usher in a new era of high-performance I/O:
“New data-intensive applications are driving demand for unprecedented levels of performance. Completing the PCIe 5.0 specification in 18 months is a major achievement, and it is due to the commitment of our members who worked diligently to evolve PCIe technology to meet the performance needs of the industry. The PCIe architecture will continue to stand as the defacto standard for high performance I/O for the foreseeable future.”
The PCIe 5.0 specification was officially released on May 29, 2019. The standard before it, PCIe 4.0 was released 2 years earlier on June 8, 2017. This was long break after the release of the PCIe 3.0 standard back in November 2010. They did however release an update, PCIe 3.1, in November 2014. So basically PCI-SIG has been releasing new standards every 2-3 years. And this makes complete sense given the rapid progression of technology/hardware and the corresponding demand of better I/O performances. But even so, the estimates PCI-SIG have presented on the performance level of PCIe 6.0 seems a tad bit too much.
The PCIe 6.0 Specification
Only weeks after the release of the PCIe 5.0 standard, PCI-SIG announced they were already hard at work in developing the next PCIe standard. The group claims that they are going to stay true to the history of their development iteration, by doubling the bandwidth of the next generation of PCIe slot. The latest PCIe 5.0 x16 slot already offers a staggering 64 GBps in bandwidth. This would mean that a x16 slot of the PCIe 6.0 specification would be able to perform I/O operations at a mind boggling 128 GBps. (That’s Giga-bytes not bits!)
PCI-SIG claims that it will implement a new kind of signaling, the PAM4 (Pulse Amplitude Modulation), in PCIe 6.0, as opposed to the NRZ used in PCIe 5.0. In their presentation, the group claimed that PAM can pack more bits per serial channel than an NRZ in the same amount of time. They will also be including low-latency FEC (Forward Error Correction) which will help improve bandwidth efficiency. It is essentially these two technologies that will allow PCIe 6.0 to be twice as fast as PCIe 5.0.
The question of everyone’s mind right now isn’t if PCI-SIG will be able to deliver this level of performance. They have delivered consistently in the past, and the group claims that they will finish the development process by the end of 2021. The more important question here is, do we really need all that bandwidth.
Rapid Advancement
PCI-SIG has been paching its iterative development cycle of the PCIe specification over the years. The group has announced that it plans to finalize PCIe 6.0 by the end of 2021. It took them nearly 14 years to get from PCIe 1.0 to PCIe 4.0. And now, in a matter of 7 years, they will have gone from PCIe 3.1 to PCIe 6.0. And they have been consistent in their practice of doubling the I/O bandwidth in every iteration. PCIe 3.0 had a rate of 8 GTps, PCIe 4.0 had 16 GTps, PCIe 5.0 has 32 GTps, and PCIe 6.0 when it is released will have a rate of 64 GTps. Question is: will we even have accelerators/video cards that require (or can make the most of) the 128 GBps rate that the PCIe 6.0 expansion slot will be able to offer?
Wven if PCI-SIG manages to release the new specification by 2021 as promised, it will still be a couple of more years before the specification reaches the mainstream consumer market. For instance, in 2019, we are finally beginning to see the emergence of the PCIe 4.0 specification released in 2017. And it will still be a couple of more years before we begin to see PCIe 5.0 reach the mainstream consumer market.
Technology is certainly accelerating, and the future is absolutely fascinating!
Expansion Slots & Expansion Cards
PCIs aren’t the only type of expansion slots out there. AGP, ISA, EISA, AMR and VESA are other types. But PCIe is by far the most popular specification today. There’s also a different type of PCIe called the ePCIe (External PCI Express). These are expansion slots that are separate from the motherboard and are connected to it with a cable.
Each PCIe expansion slot has a certain number of data lanes indicated by a number following “x”. For instance x8 expansion slots have 8 data lanes. x16 have 16 date lanes. The number of lanes in a PCIe slot determines the bandwidth of its I/O operation. High demanding hardware like a modern Graphics card require a x16 slot.
All expansion cards specify which slot they require. A card with a lower number can fit into a slot with a higher number, but the reverse will not work. For instance an x4 expansion card will fit into an x16 slot, but an x16 card will not work on an x4 slot.
Adding expansion cards
When adding a new expansion card to your computer, you will first need to remove the metal bracket in the CPU case next to the PCIe slot you are going to use. You will be able to access the I/O terminals of the expansion card through this opening. Adding the card to the expansion slot is pretty straight forward after that. All you have to do is place the gold connectors of the card into the slot and pressing gently. Many cards come with a clip to lock the cards into the slot after it has been inserted.
It is always wise to check out how many and which PCIe slots a particular motherboard offers before you purchase one. You can find this in the specifications of most motherboards. For instance, ASRock’s latest limited edition motherboard, the X570 Aqua, has 3 PCIe 4.0 x16 slots and 1 PCIe 2.0 x1 slot. Make sure the availability suits the expansion card you are planning to get. And if it’s too late and you’re running short of slots, you can always opt for an appropriate ePCIe.
PCIe slot bandwidth over the years
Here’s how the iterative PCIe standards have increased in I/O bandwidth over the years.
PCIe 1.0
Year of Release: 2003
- x1 slot bandwidth: 256 MBps
- x2 slot bandwidth: 512 MBps
- x4 slot bandwidth: 1 GBps
- x8 slot bandwidth: 2 GBps
- x16 slot bandwidth: 4 GBps
PCIe 2.0
Year of Release: 2007
- x1 slot bandwidth: 512 MBps
- x2 slot bandwidth: 1 GBps
- x4 slot bandwidth: 2 GBps
- x8 slot bandwidth: 4 GBps
- x16 slot bandwidth: 8 GBps
PCIe 3.0
Year of Release: 2010
- x1 slot bandwidth: ~1 GBps
- x2 slot bandwidth: ~2 GBps
- x4 slot bandwidth: ~4 GBps
- x8 slot bandwidth: ~8 GBps
- x16 slot bandwidth: ~16 GBps
PCIe 4.0
Year of Release: 2017
- x1 slot bandwidth: ~2 GBps
- x2 slot bandwidth: ~4 GBps
- x4 slot bandwidth: ~8 GBps
- x8 slot bandwidth: ~16 GBps
- x16 slot bandwidth: ~32 GBps
PCIe 5.0
Year of Release: 2019
- x1 slot bandwidth: ~4 GBps
- x2 slot bandwidth: ~8 GBps
- x4 slot bandwidth: ~16 GBps
- x8 slot bandwidth: ~32 GBps
- x16 slot bandwidth: ~64 GBps
PCIe 6.0
Year of Release: 2021/22
- x1 slot bandwidth: ~8 GBps
- x2 slot bandwidth: ~16 GBps
- x4 slot bandwidth: ~32 GBps
- x8 slot bandwidth: ~64 GBps
- x16 slot bandwidth: ~128 GBps
Conclusion
PCI-SIG is certainly keeping pace with the acceleration of the tech industry. They are releasing new standards much quicker than they used to, giving hardware manufacturers more incentive to improve on their particular domains. They will always need more bandwidth to improve on their technologies, and PCI-SIG is staying ahead of the curve with the rapid pace of its development iterations.
PCIe 6.0 will be released sometime in 2021/22, and it will probably start hitting the mainstream market sometime around 2023. How do you imagine the technological landscape would look like then? Leave a comment below.
