Posts: 2
Registered: ‎04-07-2019

Extremely slow

I am trying to figure out why my SSD's are running so slow (I purchased two 500gb Extreme SSD's). Connected to both USB-C and USB-A 3.1 ports on an Asus Rog Strix X470-F motherboard, both types of 3.1 ports are listing the following speeds on CrystalDiskMark 6.0.2 x64:





These are nowhere near the advertised *Up to* 500MB/s


Is there a firmware update or something that I am missing. I truly don't understand how they can be running so slow. Any help would be greatly appreciated.


Screen Cap from CDM of new SSD attached.

CDM-ExtremeSSD test.PNG
Posts: 3
Registered: ‎04-29-2019

Re: Extremely slow

That is not normal.


I think SanDisk's problems are too little that posts here just get's ignored.

If not for the water resistance, I would have just bought an M.2 drive and put

it in an enclosure.




Posts: 2
Registered: ‎04-07-2019

Re: Extremely slow

Is that the speed you are getting from yours? Something is definitely wrong with mine if that is the case.  I can't believe I've never gotten a response from Sandisk either. Lesson learned for me I guess.

Posts: 1
Registered: ‎06-02-2019

Re: Extremely slow

Hi there,

I have basically the same issue with speed, it's too low!

How can I fix it?



Popup Wordpress Builder

Posts: 1
Registered: ‎07-02-2019

Re: Extremely slow

Are you using the included USB-C to USB-A 3.0 cable? When I use the included cable I achieve the advertised speed.


When I use another USB-C to USB-A (likely 2.0) cable I do not. I think that may be your issue.

Posts: 1
Registered: ‎09-13-2019

Re: Extremely slow

I have an older laptop with three USB ports. Two are USB 2.0 and one is a powered USB 3.0. This drive performs slow in the USB 2.0 ports (similar to the posts below) with R/W speeds just over 40 mb/s - nowhere near the advertised rate of up to 500.


When I plug it into the USB 3.0 powered port, however, viola. Not quite 500, but I'll take a sequential R/W 400 Mb/s on an old machine.. 


CrystalDiskMark 6.0.2 x64 (UWP) (C) 2007-2018 hiyohiyo
                          Crystal Dew World :
* MB/s = 1,000,000 bytes/s [SATA/600 = 600,000,000 bytes/s]
* KB = 1000 bytes, KiB = 1024 bytes
   Sequential Read (Q= 32,T= 1) :   402.645 MB/s
  Sequential Write (Q= 32,T= 1) :   405.312 MB/s
  Random Read 4KiB (Q=  8,T= 8) :    64.634 MB/s [  15779.8 IOPS]
 Random Write 4KiB (Q=  8,T= 8) :    63.989 MB/s [  15622.3 IOPS]
  Random Read 4KiB (Q= 32,T= 1) :    28.137 MB/s [   6869.4 IOPS]
 Random Write 4KiB (Q= 32,T= 1) :    22.436 MB/s [   5477.5 IOPS]
  Random Read 4KiB (Q=  1,T= 1) :    12.494 MB/s [   3050.3 IOPS]
 Random Write 4KiB (Q=  1,T= 1) :    14.079 MB/s [   3437.3 IOPS]
  Test : 1024 MiB [E: 16.6% (77.1/465.8 GiB)] (x5)  [Interval=5 sec]
  Date : 2019/09/13 22:31:22
    OS : Windows 10  [10.0 Build 18362] (x64)
Posts: 1
Registered: ‎10-03-2019

Re: Extremely slow

Yes, I think so

Posts: 0

Re: Extremely slow *FIXED* *SOLUTION*

I too have experienced slow transfer rates (40 Megabytes per second) on USB 3.1 ports on a recently bought a 1TB SanDisk Extreme Portable SSD. I noticed that I was having slow transfer rates on all of the USB-C to USB-A cables I was using. I was however getting full speed on the supplied far-too-short cable.


I created an account here and posted this reply in case anyone else experiences the same problem as I have a solution. The problem is not with the SSD but with your cables!


After some research, I found that the majority of USB-C to USB-A cables are rated at USB 2.0 speeds which have a max transfer of 480 megabits per second or 48 Megabytes per second. Hence, the reason why we are only getting around 40 Megabytes per second transfer speeds!).


You need to ensure that your cables are USB-C to USB-A 3.0 which is also called 3.1 Gen 1. A USB-C to USB-C cable will also work as long as it too is 3.0 or 3.1 Gen 1 compliant.


USB 3.0 (also called USB 3.1 Gen 1) supports transfer speeds of up to 5 gigabits per second or 500 Megabytes per second.


You will need to buy ‘faster’ cables which can support 5gbps transfer rates. Carefully read the specifications. I am in the UK and bought some Anker and Amazon Basic cables sold through Amazon UK.


Search Amazon for either “ANKER POWERLINE+ USB C TO USB 3.0 CABLE” or “AMAZONBASICS USB TYPE-C TO TYPE-A 3.1 GEN 1 CABLE” and purchase those.  


I hope this helps! Take care!