What is PCIe Bifurcation and why do AMD B450 chipset skip it?

With AMD’s new B450 chipset we have been able to verify that the brand has preferred not to restrict the capabilities of its lower-end chipset, so we can do with it most of the things we need in a high-end computer, such as OC. of the processor or RAM memory. However, the differentiation between the X470 chipset and the B450 is in the possibility of making the PCIe port bifurcate or not.

The fork of the PCIe port is not something that we will use in our day to day, it is a utility from which users who need to increase the number of PCIe ports on their motherboard can benefit.

Once we turn on the computer, we determine how many devices are connected to the motherboard and identify the links between the devices. This creates a map in which traffic is planned and the bandwidth of each link is negotiated. Each PCIe connection slot contains two pairs of cables, one to send and one to receive. The information is sent through the cable in the ratio of one bit per cycle.

The smallest connection of all, PCIe x1, has four cables that transmit 1 bit per cycle in each direction. The PCIe x2 connection has eight cables and transmits 2 bits per cycle, an x4 connection transmits 4 bits and so on until reaching x16 or x32 connections.

With the fork of the PCIe port we can divide the existing slot x16 or x32 and convert it into a slot x8 / x8 or x16 / x16. There are different types of divisions, some of them are necessary to be able to use NVMe M.2 hard drives, these being the ones that are most popularizing this functionality.amd b450 base plate bifurcation port pcie.

However, in order for us to split the PCIe ports into smaller ones, we need our motherboard to have support for it. That is, we need to be able to make the settings from the BIOS, it is not worth simply connecting a switch on port x16.

So AMD has decided to leave this functionality, which also requires better circuitry inside the board and more technology, for the chipset of the high-end X470. Creating a differentiation that does not have to affect the majority of users, who currently squeeze other options such as the CPU CPU and RAM or its new StoreMI technology that “converts” the HDD into SSD.