The PCI Express standard (PCIe) was a basic requirement for connecting PC peripherals and components to a desktop. If you buy new PC parts in 2021, they will likely support the current fourth generation. With the upcoming introduction of the Alder Lake processors by Intel in the course of this year, we will switch to the fifth generation of the PCI Express interface called PCIe 5, which should enable significantly faster data transfers.
Originally introduced with preliminary specifications in 2017, the PCIe 5 standard was officially ratified by the PCI Special Interest Group in 2019. The standard is not expected to be available on PCs until late 2021, when Intel builds in PCIe Gen 5 support for its upcoming line of processors and new motherboards. What exactly is PCIe 5 and will it be a major upgrade from PCIe 4?
PCIe Gen 4 vs. PCIe Gen 5
The main difference between each generation of PCIe is speed. PCIe 1 had a bandwidth of 8 GB / s and a 2.5 GT / s (gigatransfer per second), which was clocked at a frequency of 2.5 GHz. With the current PCIe Gen 4 standard, which is used on many modern processors from AMD and Intel, the bandwidth can be up to 64 GB / s, and there is a gigatransfer maximum of 16 GT / s at a frequency of 16 GHz.
PCIe 5.0 is seen as an extension of the PCIe Gen 4 standard. With PCIe 5, bandwidth, gigatransfer and frequency are doubled compared to the previous generation, so that data can be transmitted at significantly higher speeds. Here you can see 32 gigatransfers per second or 32 GT / s, a bandwidth of 128 GB / s in an x16 configuration and a frequency of 32 GHz.
The main difference between gigatransfer (GT / s) and bandwidth (GB / s) measurement is that the former is a measure of raw speed while the latter is the data transfer rate. The raw speed measures how many bits can be transmitted per second, while the data transmission rate must also take into account the coding effort.
For example, a PCIe 5 x 8 connection means you will get a raw speed of 32 GT / s but only 31.5 GB / s bandwidth.
If you want to be among the first to adopt PCIe 5 for your next desktop build, you will have to wait until the second half of 2021 for Intel to release its Alder Lake processor family, which will be available for mobile and desktop. So far, Intel is the only company to announce support for the new standard.
According to recent leaks, Alder Lake will require a new socket and motherboard. To upgrade to this latest silicon, players will need to purchase a new board to take advantage of the latest changes, including PCIe 5 support. With a combination of architecture changes, a move to 10nm SuperFin manufacturing and PCIe 5 support, and faster DDR5 memory, Alder Lake can achieve a 2-fold increase in performance in multithreaded applications, according to the latest leak.
Because of the higher speeds, there is a greater chance of signal loss. Therefore, the standard offers features for better handling of noise and signal loss than PCIe Gen 4 to ensure data integrity.
Do you need to upgrade?
The faster transfer speeds are important for applications that include machine learning and artificial intelligence, data center use, and high-performance computing environments. This will be A.I. Applications process more data at higher speeds. Given that PCIe is the highway that connects processor, graphics card, memory, as well as FPGAs and ASIC accelerators, moving to faster PCIe Gen 5 could make cryptocurrency mining even more lucrative.
In general, most home PC users and gamers will find the speeds and capabilities of PCIe 4 – and even previous PCIe 3 – specifications to be more than adequate.
In our comparison of PCIe 4 with PCIe 3, we found that even high-performance graphics cards – such as the Nvidia GeForce RTX 2080 Ti – do not yet fully utilize the bandwidth available in a PCIe Gen 3 x16 slot. Hence, PCIe 5 will be overkill for most gamers. Like the benefits of moving from Gen 3 to Gen 4, the speed increase from PCIe Gen 5 is most beneficial for those who need faster access to NVMe storage drives and RAID configurations.
Hopefully, peripherals like GPUs connected to a PCIe slot will need fewer lanes in the future with the faster speeds. Instead of using the x16 lanes from today's PCIe 4 standard, we can reduce this requirement to PCIe 5 to just x8. With lower lane requirements to achieve similar speeds, gamers can potentially build systems that are just as powerful in a smaller, more compact tower.
What is PCIe
PCIe is known as the Interconnect Express for peripheral components that is used to connect various components of your desktop PC. This is one of the most important connectivity standards on a modern PC because different components can communicate with each other.
As an interface standard, PCIe helps you connect high-speed solid-state drives (SSDs), graphics cards, and wireless network cards to your processor. On a desktop, you connect different cards to the PCIe slot on your motherboard. The number of available PCIe slots and the type of slots depend on the card selected.
Often times, you'll find that PCIe slots and cards are labeled with a numeric value preceded by an x. The configurations include PCIe x1, x2, x4, x8, x16, and x32. These numbers indicate how many lanes are available. The higher the number, the faster data can be transferred. PCIe x1 means that there is only one lane, while PCIe x16 indicates that there are 16 lanes.
Cards and slots can be mixed and matched despite the number of tracks specified by each component, with the data bandwidth determined by the slower part. For example, if you have a PCIe x4 slot on your motherboard, you can connect a PCIe x1 card. Here your bandwidth is limited by the single available track on the card, i.e. one bit per cycle. If, on the other hand, you insert a PCIe x8 card into the PCIe x4 slot, the data is only transmitted with half the bandwidth compared to a card that was inserted into a PCIe x8 slot.
For gamers, the magic number is PCIe x16, and most GPUs require a PCIe x16 slot to take full advantage of the card's functions. Although PCIe x32 is present, it is generally expensive and rare, and most PC components lead the way in x16.