The MSI M.2 Xpander-Z Gen 4 is a dedicated PCIe Full-Height Dual M.2 expansion card designed to add extra high-speed NVMe storage slots to your computer. It was originally bundled with premium motherboards such as the: MSI TRX40. This expander is bulk-packed (as it was bundled with the motherboard). Works with software RAID.Key Specifications & Features

• Drive Support: Holds up to twoM.2 NVMe SSDs
• Interface: Designed for PCIe 4.0 x16 physical slots, though it primarily operates using PCIe lanes split into an x8 configuration (x4 per drive).
• Active Cooling: Features a shroud equipped with an integrated cooling fan to keep high-performance Gen 4 SSDs from thermal throttling.
• Physical Controls: Includes access to fan controls or switches on the card bracket to manage the onboard fan speed manually.

Critical Requirement: PCIe BifurcationThe most important thing to know before using this card is that your motherboard must support PCIe Bifurcation. [3]

• The Mechanism: This card does not have an onboard PLX/switch chip to split the PCIe lanes itself.
• The Limitation: If you plug this into a slot that doesn't support lane splitting (e.g., trying to split an x8 slot into x4/x4), the system will only detect the first SSD in slot 1.
• Motherboard Setup: You must enter your motherboard's BIOS settings and change the target PCIe slot configuration from its default mode (like x16) to a split mode (like x8/x8 or x4/x4/x4/x4).

Power ConfigurationThe card features an onboard 6-pin PCIe power connector. While it will genearlly sometimes work without it when running a couple of SSDs, connecting the 6-pin power cable is recommended. Multiple Gen 4 SSDs under heavy write loads can collectively pull more wattage than a standard PCIe slot safely provides. [7, 8]