PCIe Gen5 SSD gotchas

A new crop of PCI Express Gen 5 solid-state drives is fast enough that one wrong BIOS setting can cut performance roughly in half. (makeuseof.com) Non-volatile memory express, or NVMe, uses four PCI Express lanes like a four-lane highway, and bandwidth depends on both the lane count and the generation speed. Kingston says each new PCI Express generation doubles per-lane throughput, which is why a Gen 5 x4 drive can outrun older designs by a wide margin. (kingston.com) MakeUseOf reported on April 20, 2026 that some drives rated above 6,000 megabytes per second were benchmarking closer to 3,000 megabytes per second because the motherboard firmware had negotiated the wrong PCI Express generation. In its example, a drive rated for up to 7,300MB/s delivered 3,651MB/s read and 2,839MB/s write until the setting was corrected. (makeuseof.com) Tom’s Hardware says PCI Express 5.0 doubles raw transfer rate over PCI Express 4.0, and consumer M.2 drives on a Gen 5 x4 link now reach about 14GB/s to 15GB/s in advertised sequential reads. That makes a Gen 5 drive running as Gen 4 look less like a minor tuning issue and more like a missing half of the upgrade. (tomshardware.com, sandisk.com) The hardware itself is also changing. The SSD Review said on April 20, 2026 that Acer’s new FA300 Gen5 2TB is a DRAM-less M.2 2280 drive rated for 11GB/s reads, 10GB/s writes, and up to 1.7 million input-output operations per second. (thessdreview.com) That review framed the FA300 as a better fit for laptops and ultra-portables because it uses a Silicon Motion SM2504XT controller and a single NAND package layout that reduces heat and power draw versus bulkier Gen 5 designs. The SSD Review said those choices helped it avoid the oversized cooling hardware that early Gen 5 drives often needed. (thessdreview.com) At the high end, Western Digital’s WD_Black SN8100 pushes the other direction on raw speed. SanDisk lists up to 14,900MB/s sequential read, up to 14,000MB/s sequential write, and more than 2.3 million IOPS on 2TB to 4TB models. (sandisk.com, documents.sandisk.com) Technobezz reported on April 21, 2026 that the WD_Black SN8100 with heatsink had dropped to $334.99 on Amazon. Western Digital’s own data sheet says the heatsink version of the 1TB model can take more than 15 times longer to throttle than the non-heatsink version at a 65 degrees Celsius ambient test condition. (technobezz.com, documents.sandisk.com) The practical check is simple: compare your benchmark to the drive’s rated speed, then confirm in BIOS that the M.2 slot is using the intended PCI Express generation and lane setup. On Gen 5 storage, the difference between “installed” and “configured correctly” is now large enough to show up immediately in the numbers. (makeuseof.com, howtogeek.com)