Reason for terrible USB3 port speeds?

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WiLLiSTER

2[H]4U
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Mar 24, 2008
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I've got a Gigabyte H55N-USB3 board with my 2tb Samsung F4 external and a 16gb Cruzer flash drive (both USB2 devices) hooked up to in the USB3 slots. I'm moving various video files (ranging from about 100-500mb each) from the 2tb to the flash drive, but my transfer speed right now is ~4MB/s. I've got the NEC USB3 drivers installed, but I can't figure out why the transfer rate is so low. If I pop them both into the USB2 slot, it'll transfer at around the normal 30MB/s.

Edit: Finished 13gb of transfers on the usb3 ports. It never even hit 5MB/s :(

Edit2: Switched to my 8gb A-data flash drive and now I'm getting a whopping 9-10MB/s.
 
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some motherbords have their USB3 lane's shared with PCIE 16X (which is used by the GPU)
check the motherboard manual to make sure its not shared.
i have seen it with one of GA-H67 motherboard.
 
Another reason may be that the particular NEC USB 3.0 controller in question does not perform well in USB-to-USB transfers within the same controller. The controller performs fastest in device-to-computer transfers (or computer-to-device transfers).
 
The low write speed would make sense if the speeds were consistent on the usb2 ports. Like I said, I still get the 30MB/s usb-to-usb transfer on there.

Looks like it does share lanes with the pci-e bus. Suppose I'll just leave em on the usb2 ports for transfers. Thanks guys.
 
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