{
  "slug": "pcie-bifurcation",
  "term": "PCIe bifurcation",
  "aliases": [
    "PCI Express bifurcation"
  ],
  "definition": "PCIe bifurcation configures a supported host lane group as multiple independent PCI Express links rather than one wider link.",
  "note": "For storage, some multi-SSD adapter cards route separate lane groups to different drives and require the host to support the matching split. The cited dual-drive adapter explicitly requires host PCIe bifurcation. This requirement belongs to that design, not to every PCIe SSD. [split]\n\nA switched adapter is different: a PCIe switch on the card can connect both SSDs without host bifurcation. Check the adapter design, host slot and firmware support for the intended lane arrangement. [switch]\n\nSupport for one narrower x4 device does not imply support for four independent x4 links. Check the CPU controller, selected slot routing and firmware configuration together. [host-split] [slot-split]",
  "status": "shipping",
  "advantages": [
    "Allows a compatible host slot and adapter to expose more than one independently linked SSD. [split]"
  ],
  "limitations": [
    "Physical fit alone does not establish the required host lane configuration. [split]",
    "Bifurcation is not a universal requirement for PCIe storage. [switch]"
  ],
  "related": [
    "pcie-storage",
    "pcie-lanes",
    "pcie-switch",
    "m2"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "switch",
      "title": "StarTech PEX8M2E2: ASM2824 switched dual-SSD adapter; no host bifurcation required for this product.",
      "url": "https://media.startech.com/cms/pdfs/pex8m2e2_datasheet.pdf",
      "accessed": "2026-11-02"
    },
    {
      "id": "split",
      "title": "StarTech DUAL-M2-PCIE-CARD-B: dual-SSD adapter explicitly requiring host PCIe bifurcation; product-specific compatibility requirements.",
      "url": "https://media.startech.com/cms/pdfs/dual-m2-pcie-card-b_datasheet.pdf",
      "accessed": "2026-11-02"
    },
    {
      "id": "host-split",
      "title": "Intel 13th/14th Gen Core datasheet v009: narrower-link support versus lane bifurcation",
      "url": "https://edc.intel.com/content/www/us/en/design/products/platforms/details/raptor-lake-s/13th-generation-core-processors-datasheet-volume-1-of-2/009/pci-express-support/",
      "accessed": "2026-11-02"
    },
    {
      "id": "slot-split",
      "title": "ASUS Hyper M.2 compatibility: CPU, slot selection and firmware configuration",
      "url": "https://www.asus.com/support/faq/1037507/",
      "accessed": "2026-11-02"
    }
  ],
  "updated": "2026-11-02",
  "provenance": [
    "StarTech DUAL-M2-PCIE-CARD-B requires host bifurcation; PEX8M2E2 uses an ASM2824 switch and does not. These are documented examples, not motherboard qualification results.",
    "The host-split example is the version-009 Intel 13th/14th Gen Core datasheet, not a qualification of other processor families. [host-split]"
  ]
}