PCIe 5 vs. PCIe 4, What to Expect?

The growing number of compute-intensive applications and the launching of more advanced network technologies require a rock-solid backbone to deliver ultrafast speed. PCIe is one important backbone that needs to be constantly enhanced since it is the interface that links high-speed components like CPU and storage devices. PCIe 5.0 is the latest standard released in 2019; however, motherboards and devices supporting PCIe 5.0 are expected to debut only by the end of 2021 or early 2022. What can we expect from this new beast, and how does it differ from PCIe 4.0? Let’s first understand what PCIe is before we jump to these questions.

PCI Express (PCIe)

Peripheral Component Interconnect Express (PCIe) is a bus interface standard for connecting high-speed components such as GPUs, SSDs, RAID cards, and WiFi cards to your motherboard. PCIe is the standard slot for modern motherboards after replacing the older PCI, PCI-X, and AGP bus standards. PCIe is the pathway of data on the motherboard, and it handles data traffic more efficiently than the previous interfaces with its support for full-duplex communication between two endpoints. It comes in different lane configurations such as x1, x4, x8, x16, and x32, where the numbers signify the number of lanes; the more lanes there are, the higher the bandwidth. New versions of PCIe have always been backward compatible with the older versions allowing you to use your older PCIe cards with newer standards. However, you won’t be able to utilize the full potential of the newer standard since the capabilities will be downgraded to the lower version’s specs. For example, if you insert a PCIe 3.0 GPU into a PCIe 4.0 slot, you will get the performance of PCIe 3.0 instead of PCIe 4.0.

PCIe went through rigorous upgrades since its introduction in 2003, spanning five versions with the sixth version already on the way. PCIe 5.0 motherboards and devices are set to arrive before the year ends but will it be a worthy upgrade from the super-fast PCI 4.0?

PCIe 5 vs. PCIe 4

PCIe 4.0, as its name suggests, is the fourth generation of the PCIe interface, succeeding PCIe 3.0. It has double its predecessor’s transfer rate and bandwidth at 16GT/s and 64GBps, respectively, with an operating frequency of 16GHz. The specifications for PCIe 4.0 were out in 2017, but PCIe 4.0 motherboards, devices, and expansion cards were rolled out years after that. AMD was the first chipmaker to release motherboards supporting PCIe 4.0. Their 500-series motherboards based on x570 chipset were released in 2020. Intel followed suit, occupying the PCIe 4.0 retail space in early 2021 with the introduction of the Intel Rocket Lake CPU sitting on the Intel Z490 motherboard.

Keeping up with newer standards, PCIe 4.0 devices and PC parts like SSDs and GPUs started coming out in 2020. Some manufacturers, however, took a slower pace, releasing their PCIe 4.0 products only in 2021, when PCIe 5.0 devices are already about to set foot. In fact, many industries and manufacturers are still scrambling with the transition from PCIe 3.0 to PCIe 4.0, but they are already bracing themselves for yet another transition from PCIe 4.0 to PCIe 5.0. Backward compatibility of PCIe plays an important role in making older devices still work with newer standards while manufacturers are still struggling to keep up with the transition.

PCIe 5.0 has been abuzz since its release in 2019. It has a blazing fast raw speed of 32GT/s, doubling PCIe 4.0’s 16GT/s. Likewise, it has twice the bandwidth of PCIe 4.0 at approximately 128Gbps clocked at the frequency of 32GHz over x16 lanes. As in the case of the previous generations, PCIe 5.0 has doubled the specs of its predecessor, so we can expect PCIe 5.0-equipped devices to be twice as fast. So far, only Intel has announced support for PCIe 5.0 in their Alder Lake family of processors expected to be released in November of 2021. We are yet to hear from other chipmakers.

PCIe 5.0’s specs might be overkill for some, especially for consumers who already find PCIe 4.0’s performance more than enough for their computing needs. So why do we still need PCIe 5.0?

Unlike in the consumer space, PCIe 4.0’s specs fall short for new compute-demanding and data-intensive apps like those in data centers, AI, ML, and crypto-mining. Similarly, cloud-based applications are growing greater as more and more industries are shifting to the cloud. These applications require massive data processing, largely driving data and network traffic. Consequently, they demand ultra-high-speed components to avoid data congestion. The substantial increase in speed and bandwidth in PCIe 5.0 is therefore highly beneficial for enterprise use. PCIe 5.0 will not only make these compute-intensive apps run faster, but it will also open up more doors for system designers to develop new applications that PCIe 4.0 cannot handle.

The networking space will also need PCIe 5.0’s speed bump. Network providers need to stay ahead of the consistently growing demand for faster speed. 5G devices are starting to dominate the market, and giant companies have already addressed the need for 400G Ethernet while some have already made the shift.  PCIe 4.0’s features, although already powerful, will soon not be enough to cater to the growing demand for faster network speed and higher bandwidth, thus the need to upgrade to the much faster PCIe 5.0.

Conclusion

PCIe 5.0 is an upgrade of PCIe 4.0 in all aspects, but PCIe 4.0 is still here to stay. PCIe 5.0 is the fastest PCIe version right now, but it’s not set to penetrate the consumer market yet. While PCIe 4.0 or even PCIe 3.0’s offerings are sufficient to meet the consumer’s needs, those of PCIe 5.0 are mostly needed in enterprises that need substantially faster data processing and significantly faster network speed. We will soon start to see PCIe 5.0 motherboards and devices materialize, and enterprises will surely find it a worthy upgrade, especially that compute, and data-intensive applications require better performance from CPUs, GPUs, RAID cards, and other expansion cards.