PCIe x4 vs x16 for single NVMe SSD speed increase?

PCIe x4 vs x16 for single NVMe SSD speed increase? nvme in pcie slot Locate the PCIe slot · Insert the SSD Depending on your computer, there might be a heat sink or screw that needs to be removed prior to inserting your new nvme in pcie slot Two NVMe SSD slots on a Low-profile PCIe Card Add Your Own SSDs Add up to 16TB of SSD Storage! Super High-speed Data Transfers

nvme in pcie slot PCI-Express Gen4x4 supported NVMe SSD Storage space, 250 GB - 8 TB Form factor, 2230, 2242, 2260, 2280, 22110 Size including heat-dissipation

nvme m2 slot 2 slot and supports PCIe SSDs Most modern motherboards support this feature, some older boards had an slot but it was only able to connect to the SATA bus  cards with a B Key interface can only fit into a B Key host slot, and likewise for M Key But cards with a B+M Key design can fit in either