PCIe bifurcation is a feature that allows for flexible partitioning of data lanes in PCIe slots on supported systems. Specifically, this feature enables a PCIe x16 slot to be reconfigured into two PCIe x8 lanes, or, depending on motherboard support, divided into even smaller lanes. Importantly, PCIe bifurcation does not affect overall speed performance.
Through PCIe bifurcation, larger slots can be effectively utilized as multiple smaller slots, facilitating the use of advanced expansion cards without the need for additional PCIe bridge chips. For instance, PCIe bifurcation is particularly crucial for multi-drive NVMe M.2 expansion cards that require each drive to have its own PCIe x4 lane to function properly. Typically, a PCIe x8 to dual NVMe M.2 card needs access to two independent PCIe x4 lanes, with one allocated for each drive.
To achieve this, the traditional approach has been to use x8 cards equipped with PCIe chips specifically designed to handle this partitioning, but this often increases the complexity and cost of the card. A more streamlined and cost-effective alternative is to choose PCIe x8 cards that can natively utilize the PCIe bifurcation feature on the motherboard, which meet the requirements without the need for additional bridge chips.
