PCI Express 4.0 or simply PCIe 4.0 is the fourth generation of the standard responsible for the communication between the motherboard and the video card. The technology, which is expected to begin shipping to consumers later this year, is the replacement for so-called third-generation PCIe buses. The novelty has as differentials twice the speed of the previous version and the full compatibility with older components. For example, it will be possible to use a PCIe 3.0 card in a PCIe 4.0 slot without problems, although in this way the potential of the new PCIe will not be fully utilized.
n general terms, a PCIe 4.0 slot should look different from previous versions. The connector format is the same and anyone who has become accustomed to finding type slots on motherboards should not notice any big visual differences. What really changes is the performance, and the values tend to impress. On a 16-way interface, PCIe 4.0 must allow up to 32 GB / s (gigabytes per second) of bandwidth between the system and the peripheral mounted in the slot. The value is double PCIe 3.0, limited to 16 GB / s.
This gain is also reflected in the PCIe with less paths: in x1, it will be 2 GB / s; in x2, 4 GB / s; x4 connections (common on SSDs) will reach 8 GB / s; and eight-way x8 interfaces will be 16 GB / s on PCIe 4.0. These speed values are twice as much as the same track count reaches in PCIe 3.0.
Bandwidth: PCIe 4.0 vs. PCIe 3.0
If we consider that PCIe interfaces work in a mode that allows sending and receiving data at the same time, it can be said that the x16 bus arrives at 64 GB / s, for example. This high-speed jump should appear in evidence on two types of peripherals: video cards and NVD-based SSDs that use PCIe.
In the graphics card, the large amount of information exchanged with the system will allow for greater performance in games, but it is also expected that the user will find great advances in storage technologies. The earliest examples of PCIe 4.0-compliant SSDs are faster than 5 GB / s, well above what consumers have access to the best SSDs on the market today.
First devices and boards
The first series of PCIe 4.0-compliant products arrives from July, when AMD Ryzen 3 processors and X570 chipsets debut in the market, promoting support for the technology. In addition to these products, essential for the beginning of the popularization of the new standard, the first SSDs compatible with this interface are already appearing. Corsair, for example, has unveiled a M.2-slotted model that can reach read speeds of 4,950 MB / s (megabytes per second), virtually 5 GB / s.
The Gigabyte model is even more impressive. The Aorus gen4 has 2 TB of capacity and uses a PCIe 4.0 x4 interface (four-way, therefore). The technology achieves speeds greater than 15 GB / s write and read in a RAID0 configuration. The performance of the SSD is so high that the unit comes with its own fan and dedicated cooling system.
In fact, temperature and consumption can become a problem in the first applications of the technology. For example, Asus’s Crosshair motherboards, supporting PCIe 4.0, have been demonstrated with a large cooling system, which works on the chipset (type of motherboard coprocessor that controls input and output is the case of PCIe slots).
What about video cards?
Graphics cards with PCIe 4.0 standard already exist. AMD‘s Radeon Instinct MI60s are technology-compatible, but designed for data centers. Radeon VII, which uses the same architecture, is connected via PCIe 3.0 because, according to the manufacturer, desktops still do not need the high speed of PCIe 4.0 for graphics applications. However, this may change, and support for PCIe 4.0 should become broader in the coming months: Radeon’s future Radeon RX 5000 series should bring technology to home users.
PCIe 5.0 is coming
PCI-SIG, a consortium that defines the technical standards and manages the PCIe application over the years, has already finalized the PCIe 5.0 technical specifications. There are even chances that the new standard will be implemented commercially by 2020, something that could make PCIe 4.0 obsolete in a few months.
This situation may end up because the process of defining PCIe 4.0 and its implementation in the market has been delayed for some years. In any case, when it comes to the consumer, PCI Express 5.0 should bring the same PCIe 4.0 performance leap: twice as fast, with bandwidth in the 128 GB / s range for 16-way (x16) connections.