AS Media's ASM2824 has a PCIe 3.0 x8 upstream port as well as 4 PCIe 3.0 x4 downstream ports. The switch is designed primarily for storage devices.
SI-PEX40157 card uses ASM2824 switches and therefore does not rely on PCIe bifurcation supported by CPU or PCH (they will work on closed end systems that have limited PCIe bifurcation capabilities).
Dedicated PCIe 3.0 x8 bus bandwidth fully maximizes NVMe SSDs performance
Delivers unprecedented fast transfer speed via intelligently aggregated QUAD x4 PCIe 3.0 bus bandwidth
NVMe RAID is supported base on the motherboard chipsets