1. #1

    What speed is USB 3.0 supposed to be, realistically?

    Anyone have some numbers for me? My usb slots have been acting up for awhile with my system saying I should plug my external hdd into a usb 3 slot so it can run faster, even though it was. I thought I had fixed this for awhile by downloading the Asmedia download from this page but I got the message again today that the usb 3 wasn't recognized. I re downloaded asmedia and I haven't gotten the message, but I want to check if it's running at USB 3 speeds.

    Right now I'm getting around 77.0 mbps when transferring files from my pc to my external hdd.

    Thoughts?

  2. #2
    The Lightbringer Shakadam's Avatar
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    Are you talking megabytes or megabits? If bytes, that sounds perfectly reasonable. If bits, that would be less than 10MB/s and that's definitely slow.

    USB 3.0 (which doesn't exist anymore btw) caps out at 5Gbit/s or 625 MB/s but obviously a HDD won't get anywhere even close to this.

    Since USB 3 is a complete clusterfuck when it comes to naming I'll list the ones that exist:

    USB 3.2 Gen 1 – 5 Gbit/s (1 lane)
    USB 3.2 Gen 2 – 10 Gbit/s (1 lane)
    USB 3.2 Gen 1×2 - 10 Gbit/s (2 lanes)
    USB 3.2 Gen 2×2 – 20 Gbit/s (2 lanes)


    USB 3.2 Gen 1 is the same as the old USB 3.1 Gen 1 and USB 3.0
    USB 3.2 Gen 2 is the same as the old USB 3.1 Gen 2

    Confusing? Yeah.

  3. #3
    Quote Originally Posted by Shakadam View Post
    Since USB 3 is a complete clusterfuck when it comes to naming I'll list the ones that exist:

    USB 3.2 Gen 1 – 5 Gbit/s (1 lane)
    USB 3.2 Gen 2 – 10 Gbit/s (1 lane)
    USB 3.2 Gen 1×2 - 10 Gbit/s (2 lanes)
    USB 3.2 Gen 2×2 – 20 Gbit/s (2 lanes)
    Something else to keep in mind is that the actual speeds you will get can depend on the number of other devices which are connected. Some boards are setup in such a way that they'll group USB-3 ports, and split the speed equally between all ports which have devices connected.

    So, if you have a mouse connected to port 1, and port 1 is sharing it's bandwidth with port 2, then you may not be getting the full USB-3 speed if you connect a drive to port 2.

    Also keep in mind that different workloads will cause the speeds to fluctuate significantly. Sequentially writing large files generally offers the most stable performance, but this can drop if the external drive has a cache. Many smaller files being written to a HDD will absolutely tank the write speeds.

  4. #4
    Quote Originally Posted by Season2mask View Post
    Right now I'm getting around 77.0 mbps when transferring files from my pc to my external hdd.
    77 mbps would be pretty slow, 77 MB per second is to be expected from an external HDD.

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