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Need help (MB/s question)

  1. Jan 11, 2008 #1
    I don't think this should be hard, but it is to me for some reason.

    Ok, I want to know how many MB per second my USB flash drives are writing. I wrote 723MB to each drive and timed it with a stopwatch.

    first drive took 7 mins 31 seconds
    second drive took 3 mins 18 seconds
    third drive took 8 mins 51 seconds
  2. jcsd
  3. Jan 11, 2008 #2
    I know it takes a few seconds to initialize when a file is started, since it has to use memory caching and such. You can calculate an average over time by MB / T. Where MB is the Megabytes, and T is the time.

    A better way would be to time the MB transferred at certain time intervals. Like every 5 seconds. Then you'd get a graph. You'll probably find as time goes on it gets faster.

    It sounds like your differences may be due to USB 1 vs USB 2 flash drives.
  4. Jan 11, 2008 #3
    Actually, all three of these drives are newer and utilize USB 2.0 tech (my motherboard also supports 2.0). However, two of them use dual-channel technology (first and second drive) and the other doesn't.

    From the manufacturer specs, the first drive claims a write speed of 14-15MB/s, the second drive claims 17MB/s, and the third actually claims up to 20MB/s. I guess it's the dual-channel that is making the first two drives faster. I know your southbridge can make a big difference in how fast a flash drive will perform because that's where the USB controller is located so I tested all of the drives on the same motherboard. I've been told by a tech representative of one of my drives that the size of the drive also makes a difference, with the smaller capacity drives performing faster than the larger. He said the difference would be no more than 1MB/s. The first drive is 2GB and the other two are both 1GB.

    Thanks for your quick reply.
    Last edited: Jan 11, 2008
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