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Will the M2N78-LA (Violet6) throttle a USB 3.0 PCIe x1 Card?

Last response: in Motherboards
June 19, 2012 4:58:34 PM


Apologies in advance if this belongs in the storage forums, but my question seems a bit more directed at the motherboard.

I was recently given a HP p6310y, and added a Rosewill RC-505 USB 3.0 PCIe x1 card (

*HP p6310y specs:


The Rosewill RC-505 uses a Renesas µPD720200A USB 3.0 Host Controller, and I updated the drivers and firmware after poking around online since the firmware update supplied by Rosewill would hang and then crash. Downloaded the new drivers here:

I have also attached a Molex connector to the port on the RC-505.

Then tested transfer speeds with a USB 3.0 WD My Passport 1TB 2.5 HDD and could move small files at around 64 MB/s.

Using AJA disk speed test showed Read/Write around 88-90 MB/s.

These numbers are fairly slower than my internal Sata II speeds as well as eSata (again, Sata II). I was anticipating that USB 3.0 would yield higher read/writes and file transfer speeds than Sata II. (Realizing that the USB 3.0 card is only PCIe x1, it should still have a throughput of 500MB/s in one direction since the PCIe version is 2.0, correct?)

So, contacted Rosewill Tech Support to ask why the slow speeds, and the tech explained that the motherboard must not be able to handle the USB 3.0 speeds via its PCIe bus.

So, esteemed and knowledgeable folk of Tom's, I turn to you... does the M2N78-LA (Violet6) mobo throttle USB 3.0 speeds via PCIe x1?

*M2N78-LA specs:


Thanks very much in advance for helping a novice.
a c 1131 V Motherboard
a b α HP
June 19, 2012 11:23:51 PM

Do not forget that there is a regular HDD in your external casing and the fastest mechanical drives just exceeded the speed of SATA 150, not one of those in there. Try a USB 3 memory stick (nand flash) and then you will actually task the card.