The PCI Express bus is mainly used by graphics cards that need to stream data to the memory that is then used to generate the displayed scenes. However, more and more devices are emerging that are connected to the PCIe bus. Recently, the PCI-SIG organization has released the PCIe 4.0 standard, which means that soon the motherboards and other devices will be released.
There is no revolution here. As expected, new solution is faster and more economical. The new version of the standard allows for twice as fast data transfer as possible in PCIe 3.0. Energy-saving features have also been improved, which is particularly important for modern graphics cards. After all, we do not want our computer to consume unimaginable energy when it only displays the Windows desktop.
PCIe 4.0 bandwidth is 64 GB/s.
So far, graphics cards have much lower requirements when it comes to data transfer. The PCI-SIG organization notes that new PCIe 4.0 buses will be used in cloud computing and data storage industries. SSDs are already well-established in our computers, but they are not the most efficient solution. Much faster are SSDs that use the NVMe interface and are mounted on boards with PCI Express bus. Currently, these modules use PCIe 3.0 and x4 provide sequential read speeds of over 2 GB/s. On the other hand, the write speed is roughly half, i.e. almost 1 GB/s. Unfortunately, the cost of such a medium with a capacity of 400 GB is an expense of about Rs 44 000.
PCIe 5.0 will also be twice as fast as PCIe 4.0.
PCI-SIG ensures that the PCI bus will never become a bottleneck for new technical solutions. That is why they have just announced another solution, the PCIe 5.0, which is expected to hit the market in 2019. What will be the application of a new bus with a total throughput of 128 GB/s? If we look at this issue for bidirectional full duplex data transfer, then we get “only” 64 GB/s. This is the speed which you need to use fiber-optic 400 Gbps Ethernet cards. It is true that none of us will install them in home PCs, but they will certainly be used in servers that support astronomical traffic.