What is PCIE？
PCI-Express, abbreviated as PCIe, is a high-speed serial computer bus standard designed specifically for connecting high-speed components. On desktop computer motherboards, you will find numerous PCIe slots, which provide possibilities for the expansion of general-purpose graphics cards, various peripheral cards, wireless network cards, solid-state drives, and more. The types of PCIe slots available mainly depend on the motherboard you purchase.
These PCIe slots differ in physical configuration, including types such as x1, x4, x8, x16, and x32. The value following the number x indicates the number of lanes for the PCIe slot, which determines how data is transmitted to and from the PCIe card. For example, a PCIe x1 slot has one lane, with a data transmission speed of one bit per cycle; whereas a PCIe x2 slot provides two lanes, with a transmission speed of two bits per cycle.
PCIe adopts a high-speed serial point-to-point dual channel high bandwidth transmission method, ensuring that the connected devices can enjoy the channel bandwidth exclusively, thereby avoiding the sharing of bus bandwidth. In addition, PCIe not only exists in the form of M.2 interface channels, but also appears in the form of PCIe standard slots.
PCIe slots and channels
PCIe has excellent scalability and can support a wide range of devices, such as graphics cards, solid-state drives with PCIe interfaces, wireless network cards, wired network cards, sound cards, video capture cards, etc. In addition, PCIe also provides adapter options such as PCIe adapter M.2 interface, PCIe adapter USB interface, and PCIe adapter Type-C interface, further enriching its application scenarios. It is worth noting that the M.2 interface channel is also a type of PCIe interface, mainly used for inserting solid-state drives that support M.2.
The Application and Future of PCIe
PCIe devices and adapter options
The bus bandwidth of PCIe interfaces is distinguished based on length, including PCIe X1, PCIe X2, PCIe X4, PCIe X8, and PCIe X16. Among them, Thunderbolt 3 with full blood usually refers to PCIe X4, while Thunderbolt 3 with residual blood refers to PCIe X2. These different bandwidth levels mean that the supported speeds will also vary. The problem of PCIe and M.2 sockets not coexisting is due to their sharing of the same PCIe bandwidth channel. When using one, the other will not work.
PCIe speed and new versions
With the continuous growth of bandwidth demand for peripheral interconnection, PCIe technology is constantly advancing and gradually upgrading together with SerDes technology. Nowadays, we are about to usher in the PCIe 7.0 era. What kind of PCIe technology innovation will it bring in the future? Looking back at history, we can see the different versions of PCIe and their corresponding speeds:
- PCIe 1.0, Gen1, 2.5Gbps per channel
- PCIe 2.0, Gen2, 5Gbps per channel
- PCIe 3.0, Gen3, 8Gbps per channel
- PCIe 4.0, Gen4, 16Gbps per channel
- PCIe 5.0, Gen5, 32Gbps per channel
- Currently under development, PCIe 6.0, Gen6, is expected to reach 64Gbps per channel and adopt PAM4 encoding.
