PCIe 4.0 (Gen4) NVMe SSDs in Canada

PCIe 4.0 x4 gives an M.2 drive about twice the bandwidth of PCIe 3.0, close to 8 GB/s in theory. High-end Gen4 drives such as the Samsung 990 PRO and WD_BLACK SN850X are rated at up to 7,000–7,450 MB/s sequential reads; value models like the Crucial P3 Plus and Kingston NV3 are rated lower. Each product page lists the rated speeds.

Yes. PCIe is backward compatible, so a Gen4 NVMe SSD works in a Gen3 M.2 slot at Gen3 speed (about 3,500 MB/s). Check that the slot supports NVMe rather than SATA only, and that it takes the drive length, usually M.2 2280.

Gen5 drives need an M.2 slot wired for PCIe 5.0 and run hotter. For gaming and everyday work a fast Gen4 drive feels much the same and usually costs less; Gen5 helps most with very large file transfers. In a PS5 or a Gen4 motherboard, a Gen5 drive runs at Gen4 speed.

Not for most people. Higher-end Gen4 drives such as the Samsung 990 PRO and WD_BLACK SN850X have a DRAM cache that helps hold their speed under heavy, mixed workloads. DRAM-less Gen4 drives use Host Memory Buffer (HMB), borrowing a little system RAM instead; they are fine for gaming and everyday use but can slow down more during very large sustained writes.

If your motherboard or laptop has a Gen4 M.2 slot, yes: Gen4 roughly doubles sequential speed (about 7,000 MB/s against 3,500 MB/s), which shows most in large file copies and game installs. Boot times and everyday app loading feel similar. A Gen4 drive also works in a Gen3 slot, at Gen3 speed.