I recently bought a Samsung 970 evo plus 250gb drive. It worked really fast when I bought it . When I copied a file today I had very slow write speed (50-100 mbps). No thermal throttling. Latest nvme driver and firmware.
Celeron n4000, 4gb ddr4 2400mhz, windows 11, 1tb hdd and Samsung 970 evo plus.
Lenovo Ideapad S145 15Igm
Everything is free. Boot drive is a hdd. Using pcie gen 2 as my laptop does not support pcie gen 3. Ssd used to have speeds of 1.6gb/s in both windows 10 and 11. benchmark in magician shows 1.7gb/s in read and write while windows explorer showed only 70-90 mb/s when copying files.
The Magician benchmark looks ok but, if you are using Windows to copy files to and from the hdd then the transfer rates are going to be limited by the hdd and Win performance not the 970.
The best thing would be to replace the mechanical hdd with a Sata SSD.