Posts: 3
Registered: ‎02-07-2018

ExtremePro USB 3.1 128GB Writes Slow but Reads Fast

[ Edited ]



TL;DR: read speeds are fine, only write is slow. drive is 9 months old, has written ~500GB in total, tested on three different systems (2x USB 3.0, 1x USB 3.1) with equal results on all of them: Overall slow and inconsistent write speeds even when transferring just one large file. Also occasional hang ups where the write speed goes down to 0 MB/s for a few seconds. Tried fast and slow reformatting to exFAT and NTFS, made no difference. Is the drive defective?



I have slow and inconsistend write speeds with my ExtremePro USB 3.1 128GB  (SDCZ880-128G) flash drive. However, read speeds are blazing fast (~380 MB/s).


The write performance is very inconsistent and overall slow. Especially considering the advertised write speeds of "up to" 380 MB/s. I know those are never true but I expect at least 80% of the advertised speeds (~300 MB/s). But even with single large files I only get a very inconsistend 100-200 MB/s. You can see what I mean by inconsistent in this screenshot.


Transfer of a single 12GB file from internal Samsung 960 EVO (NVMe) over USB 3.1. Filesystem is exFAT


General system load is definitely NOT the cause of the inconsistent speeds, there is no other disk activity and no other programs are running. The drive behaves similar on all systems I have tested it on. It also occasionally hang ups for a few seconds where transfer speed goes down to 0 MB/s. Another user experienced similar hangups in this thread.


I have no idea what could cause these problems. The drive is 9 months old and was not used much. Even including performance benchmarks, the drive can't have written more than 500GB. I mostly transfer many small files.It is also not only an issue on one particular system.  I have tested the drive on the following systems. All of them have latest drivers and the USB ports function properly.


- System 1

Model: ThinkPad X230

OS: Windows 10 (1709)

Internal Drive: Samsung 840 EVO 256GB (SATA3)

USB Port version: 3.0


- System 2

Mainboard: Gigabyte Z370-HD3P

Windows 10 (1709)

Internal Drive: Samsung 960 EVO 512 (NVMe)

USB Port version: 3.1


- System 3

Model: MSI GE60-0ND

OS: Windows 10 (1709)

Internal Drive: OCZ Vertex4 128GB (SATA3)

USB Port version: 3.0


On all three systems I get similar results to this:



Benchmark on System 2 over USB 3.1. Filesystem is exFAT. Note the really fast read speeds but slow write speeds.


I can't find other users with similar bad performance on google, so maybe the drive is defective after all. Do you guys have any ideas or suggestions? Is there a way to "hard reset" the drive because it was a lot faster in the first few months. It got slower and slower over time.


Thank you for reading and your time!

SanDisk Guru
Posts: 2,836
Registered: ‎07-23-2010

Re: ExtremePro USB 3.1 128GB Writes Slow but Reads Fast

Are you using bitlocker too?  Or SecureAccess?  When writing to the drive?

Important files = Backed up files
Posts: 5
Registered: ‎02-07-2018

Re: ExtremePro USB 3.1 128GB Writes Slow but Reads Fast

Here are the Crystaldisk bench I got with a 256GB Extreme PRO USB 3.1 stick

Yes, performances are not as expected !

Posts: 3
Registered: ‎02-07-2018

Re: ExtremePro USB 3.1 128GB Writes Slow but Reads Fast

[ Edited ]

@ Ed_P :

I am not using anything like that. Just regular file access to the regular exFAT-formatted drive.


@ 100PIER :

Thanks for sharing your benchmark results!

Do you also have varying write speeds like in my first screenshot when copying a single large file to the drive? Or is the write speed (nearly) constant on your drive?

Posts: 1
Registered: ‎03-15-2019

Re: ExtremePro USB 3.1 128GB Writes Slow but Reads Fast

i am also facing similar problem 

write speed suddenly goes down to zero

i used a bit locker then removed it

still the problem is same

also the bench mark results are so poor