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  • USB 3.0 slows down by a factor of 10x when not used

    Home Forums AskWoody support PC hardware USB 3.0 slows down by a factor of 10x when not used

    • Author
      • firstmerk
        AskWoody Plus

        I have an SSD in a USB 3.0 cassette, and a Sabrent Rocket in an NMVE gumstick’ cassette.
        If I have a FRESHLY booted Win10Pro 1909 and I do a CrystalDiskMark speed test on it I get 430 MB/s Read/Writer transfer. Happy with that.

        If I’m using the PC for X hours, and I want to copy/transfer some files, it operates like a slug. When I test it again using CrystalDiskMark the speed is now 34 MB/s Read/Write.

        It does the same thing with fast USB3 flash drives also, dropping to that 34 MB/s, though they never do go as fast. The slower max speed is expected, depending on the drive.

        Device Manager says everything is working properly. Trying to update the driver does nothing. Uninstalling > re-installing the drivers make the speed ‘pop back up’, but they after some time they slow WAY down……again. One USB set is off the MB, the other one is a USB 3.0 add-on card. Drivers load automatically from Windows10. I cannot find any proprietary drivers.

        I HAVE unchecked [allow the computer to turn off this device to save power]. Made absolutely no difference.

      • #2357259
        AskWoody Plus

        Try disabling your A/V and any other HDD/SSD monitoring app when running speed tests.

        • #2357300
          AskWoody Plus

          When testing I try to not have anything else running. A re-boot, which brings the speed back would be clearing everything out?

      • #2357254

        When transfers are slow, check that the USB drives and the USB ports are all running at 3.0 (SuperSpeed).

        The portable program “USB Device Tree Viewer” will tell you that info (and more):

        • #2357301
          AskWoody Plus

          That looks…uh, technical, and somewhat daunting.

          • #2357996

            I suggested that you verify that your USB drives are actually running at USB 3.0 speeds. The slow speed you have observed is consistent with a drive that is running at USB 2.1 speed.

            As a test, I attached a Samsung T5 to a 3.0 port under W10 20h2, and got 461 mb/sec on Crystalmark.  Then I switched to a 2.1 port and got 34 mb/sec so that performance drop is consistent with what you have reported.

            I worked on a Sony Vaio running 1909 and I found that intermittently a 3.o drive plugged into a 3.0 port would be incorrectly recognized as a 2.1 drive.   I traced the problem to the Microsoft USB 3.0 driver which was not completely compatible with the Intel driver that was originally installed on the machine under Windows 7.   I found that a restart or a re-install of the driver resolved the problem but only temporarily.  A newer 3.0 driver installed after an upgrade to 20h2 seems to work better.

            All that being said, are you sure that your drives are consistently being recognized as 3.0 drives?  You can verify using Device Manager but I found the tree presented in DM to be confusing.  That is why I recommended “USB Device Tree Viewer”.  Click on a device in the tree in that program and a summary section will tell you clearly the speed of the port, the speed of the device, and the speed of the connection.

            In Windows, you can also look at Settings, Devices, Bluetooth and Other Devices.  It might show you whether the drive is attached as 3.0, or could perform faster if attached to 3.0.  That Settings doesn’t seem to report all the USB devices, so I am not sure of its accuracy.


            • #2358300
              AskWoody Plus

              Compelling argument. I’ll have to take a look at that.
              I do have a test bed with W10 20h2, but it’s on a different PC with a different chipset so not sure it that would be an accurate comparison.


      • #2358445
        AskWoody Plus

        What is your PC model or motherboard model?

      • #2358447
        AskWoody Plus

        Asrock Z75 Pro, Intel Z75 chipset, i5 3570 CPU,  16MB DDR3 RAM
        In addition to the USB 3.0 ports of the motherboard, I’ve added a PCIe Renas USB 3.0/HP-SU1 USB.
        USB 3.0 from both port systems act the same.

      • #2358528
        AskWoody Plus

        Perhaps test your USB3 drive I/O performance by plugging it into one of motherboard’s two rear USB3 ports. Those ports are shielded.

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