Share via

USB 2.0 limit actually only 30mb/s not 480mb/s? USB 3 was the fix?

Anonymous
2010-09-16T12:54:04+00:00

Hi. I was talking to a reps in a computer store. They all pretty much told me that usb2 has a limit of about 30-35 mb/s transfer speed at most. Is this true? They mentioned the hardware, but is it Windows XP, Vista or 7? Is this the same on a Mac or in Linux?

I have noticed when I move large amoutns of info and leave an external drive alone, it speeds up and can go quite fast, but I do not have a program to bench mark my usb ports or devices.

I was told and have learned solid sate drives and HDD with faster rpm's helps deal with any bottlenecks and slowdowns. Especially when transfering from two locations in your computer or to multiple devices which slows down.

So if I get a pci card that has 3 or 4 usb2 ports: Will they share mb/s? (transfer or bus speed?) I thought that pci cards are faster and that the sharing of transfer speeds is less? What about seperate usb ports, do they share since they are on the motherboard?

Is there any way to maximize the capability of a usb2 port to make it as fast as possible? And if there is quite a limit, why is it still marketed as 480mb/s?

If there's a better site to ask, please tell me. If anyone has somesort f program to monitor the usb ports can you post a link?

I was also told that ESata and Firewire do not have this limitation.

Windows for home | Previous Windows versions | Devices and drivers

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

0 comments
Answer accepted by question author
  1. Anonymous
    2010-09-18T10:20:42+00:00

    To summarise:

    USB 2.0 clock speed is 480 megabits per second. That's 60 megabytes per second. Given the protocol overhead and the fact that USB 2.0 is half-duplex, the maximum data rate will be 30-40 megabytes per second. The 480 megabits per second limit applies to the USB controller and is shared between the ports attached to it. The number of USB controllers per card or motherboard will vary.

    100+ people found this answer helpful.
    0 comments

4 additional answers

Sort by: Most helpful
Most helpful Newest Oldest
  1. Anonymous
    2010-09-19T09:33:53+00:00

    You have to research your motherboard and PCI card to find out how many USB controllers they have. Each controller will have have its own 480 Mb/s. The motherboard and PCI card will operate independently.

    The transfer rates for Firewire and eSATA are also quoted in megabits. A good starting point to find information on actual performance is the Wikipedia articles

    http://en.wikipedia.org/wiki/FireWire

    http://en.wikipedia.org/wiki/ESATA#eSATA

    The best performance for external disk drives will be obtained with eSATA. With appropriate controllers and drivers the performance will be the same as an internal disk.

    1 person found this answer helpful.
    0 comments
  2. Anonymous
    2010-09-19T02:06:17+00:00

    Ok, so when I plug into the motherboards usb ports, or into a pci card with usb posts, and maybe a usb hub: The transfer speed is shared. (?)

    Now: Will a pci card I can install in the back have it's own 480 megabits per second, and the motherboard have it's own 480 megabits per second max each? Or will that also be shared?

    Since I looked at firewire 400 and 800: it is also megabits per second not in Megabytes? And they share also? I am confused since reps told me Firewire and ESata do not experience this as usb does.

    Thank you.

    0 comments
  3. Anonymous
    2010-09-18T03:43:16+00:00

    Great. I was typing fast, I had to go to work. Yes I was a bit confused. I read both sites, and bookmarked the USB monitor program.

    Thank you.

    0 comments