Question About USB 3.0

I have a Seagate GoFlex 1 TB Portable External HD. Whenever I plug it into one of the USB 3.0 ports on my new computer, it says "this device will perform faster in a 3.0 port". I KNOW that I am putting it into the right port. I have 3 USB 3.0 ports and two 2.0 ports, and I get the same message in all of them.

In the Device Manager, it says that I have the 3.0 drivers installed and working properly. My transfer rate in the 2.0 ports when I copy a 2GB movie from my external HD to my desktop is about 24 MB/s. In the 3.0 port, it is about 40 MB/s.

I called my computer's manufacturer (Power Notebooks), and was told that 40 MB/s for USB 3.0 is pretty normal, and that the higher speeds are "burst" speeds, and not every device is going to manage speeds like that. He said his own 3.0 devices only get 30 MB/s.

Funny thing is, I was getting about 100 MB/s for about two minutes the other day with the same external HD. I then moved the HD a little bit, which jiggled the cable, and the speed kicked back down to 40 MB/s.

So, is 40 MB/s a normal transfer speed for USB 3.0? Or should I be worried about having to send my computer out for repair? Or does it sound like a problem with the external HD itself? Thanks.

 

There's some overhead to copying. With a PCIe to USB3 adapter, I get 200MB/s sequential speeds and around 25~30MB/s random 4K when tested with CrystalDiskMark and AS-SSD but the highest sustained file copy I've seen is ~50MB/s (10GB VHD: USB3 SSD to USB3 SSD). Try testing your external's speed with CrystalDiskMark (reduce size from 1000MB to 100MB) to see the raw throughput it's capable of.

 

or it could be your USB cable that is giving problems.

USB2 maxes out at about 30MB/s, USB3 should be with times more than that.

 

That's what I was thinking.

I've already ordered a replacement cable for it, but with Hurricane Sandy holding up Amazon's shipping, and me without power until Wednesday (or so they say), I don't know when I'll get it.

 

Have you tried benching with CrystalDiskMark? That should show you max throughput for your USB3 controller + external HDD combination and you don't have to wait for shipping or anything. Raw throughput rarely translates to the same file copy speeds.

 

Indeed, small file transfers will be slower, it's large file transfers that can attain the max throughput of the device.

In rare cases, you can see USB2.0 up to 35 MB/s-40 MB/s, but i've only seen 35 once or twice myself and 40 MB/s in a review somewhere, never encountered that kind of speed irl. The best i've been able to do on USB3.0 is ~200MB/s and that was with a SSD. I've seen as low as 40MB/s reported speed for files that were in the few MB to few kB range on USB3.0.