Write speed issues - Sandisk Extreme Pro USB

5 Jul 2007
Had a 512Gb pen drive for a year or so and enjoyed write speeds around the 200Mb/s. Upgraded to a 1Tb model today and write speeds on the new drive are down to around 70-100Mb/s ?. Initially write speed is around the expected 400Mb/s but quickly drops after around 3 seconds or so. I tried transferring a file to my old 512Gb and that's dropped to around 100Mb/s too ??. Source file on a very fast M2 drive (around 5Gb/s) so no problem there. Same speed drop if copying from old to new USB key.

Both keys formatted NTFS 4096 byte allocation (ExFAT 256Kb allocation makes no difference)

USB3 'SS-10' port. Both drives policy 'quick removal' ('better performance' only gives a short boost before again dropping speed). PC restarted, no improvement at all.

What's the game here ??
10 Jul 2010
This why I gave up using USB sticks, they aren't reliable enough. The best move I ever made was buying a USB NVME enclosure and put an M.2 drive in it. It is constantly faster and the transfer speeds don't suddenly drop for no reason.
Man of Honour
13 Oct 2006
I've had more joy with micro SD cards in a USB adapter than with some of the latest and greatest USB sticks :( 16-32GB ones seem fine but some of the latest 128+GB seem to struggle with sustained writes. One I was using recently (genuine) was slowing down to mere 100s of KB/s (even when writing large files) after 0.5-20GB of continuous writing depending on file patterns due to a mixture of thermal throttling and a naff controller/cache setup.
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