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I'm looking for an adapter that will let me use a USB 3 port as a Gigabit Ethernet port. This is proving surprisingly hard to find! Is there some reason why this product is either unavailable or very obscure? Is there an online shop (US/Canada) where I can buy such an item? Newegg, TigerDirect, NCIX, etc. do not seem to carry such an item. I find this surprising since it will provide at least double the bandwidth (possibly quadruple) compared to a USB 2 Gigabit Ethernet adapter.

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Firstly, no gigabit adapter plugged into a network will get anywhere near the maximum speed. USB 2 provides a theoretical maximum that is "good enough". For what it's worth, I have a USB 2 / ethernet adapter and it's good enough for me. I see around 200 - 250Mbps. –  user3463 Jan 21 '12 at 3:27
@Randolph West: I've found that USB2 tends to max out at about 30MB/s for drives; this agrees with your findings for the ethernet adaptor. Tom's Hardware got speeds of about 111MB/s on a gigabit network (compared to the theoretical maximum of 125 MB/s). My drives aren't that fast (yet), but they're at least twice 30MB/s, so it's worth it for me to use USB 3. –  intuited Jan 21 '12 at 4:01
Shopping recommendations are off-topic according to the FAQ. –  Ƭᴇcʜιᴇ007 Jan 21 '12 at 4:20
@techie007: Duly noted. The main point of the question is to ask why they are difficult to find, so the question is I think still valid. –  intuited Jan 21 '12 at 4:41
@RandolphWest that's simply not true. Decent network kit,and crtically decent ethernet adapters, will happily saturate 1Gbps networks. I regularly get 100MB/s copying over gig ethernet to/from SSD equipped laptops. –  Dean Smith Jun 15 '12 at 14:45

4 Answers 4

up vote 8 down vote accepted

We've also been looking for these for a long time, but no one made a USB 3.0 until just this year. We ended up buying some adapters from this place http://www.usb3gigabit.com/.

But we needed them for a different purpose - we don't do virtualization but needed to add second full gigabit port to the laptops we send out to be used as network diagnostics equipment. We used to use ExpressCard before, but laptops don't have this slot anymore, so had to get the USB 3.0 to gigabit adapter. All others wouldn't actually run at full gigabit speed despite showing it. The throughput of USB 2.0 was too low.

As to why it took so long - very simple actually - nobody thought this was a product worth making until Axis decided to do it. Once they made the chip, PCB layout and programming of the chip - at least 3 companies are making the adapters. All of them are based on the same AX88179 chip, but the one on the site above is the cheapest we could find.

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Possible reasons:

  • USB 3.0 is relatively new.
  • Gigabit ports have been standard on motherboards for awhile (some even have two), so it's not like it was in the 1990s where a network adapter was virtually guaranteed to be an add-on item for a PC.
  • USB 1.1 and 2.0 (and possibly to some extent 3.0, not sure) are CPU driven interfaces - great for convenience but bad when you want the maximum performance from a device such as a hard drive or a network adapter - no one usually tries to use USB for fast networking. Many who would need such an additional interface would install a PCI/PCI-Express card.

That being said I'm sure one will pop up eventually.

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I've not noticed high CPU usage when accessing a USB hard drive. Are you saying this should be the case? –  intuited Jan 21 '12 at 17:39
@intuited CPU usage from USB data transfer is typically in the low single digit percentages. What you mainly get is extra latency. The USB controller can't directly read/write data to memory or to disk. Instead, every time it receives a new chunk of data or finishing sending the one it was working on it has to ask the CPU to transfer data to/from the rest of the computer for it. Because the CPU can't respond instantly to the request there're frequent smaller pauses in USB data transfer. This is why USB2 maxes out at about 65-75% of its theoretical speed. –  Dan Neely Feb 17 '12 at 19:55

I know this really old, but here are 2 products:

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Awesome! Very useful, but I don't know if I can accept this answer, since it doesn't address the question of why it took so long for a product like this to hit the market. OTOH I guess it proves that the product in question is not (any longer) unavailable. Note that the first link gives Availability as "Coming Soon" –  intuited Aug 21 '12 at 19:12

This does exist, see http://www.eetimes.com/electronics-products/electronic-product-reviews/logic-interfaces-products/4233735/ASIX-releases-the-world-s-first-single-chip-USB-3-0-to-gigabit-Ethernet-controller

However I've yet to see anyone build a product from this chip, which is disappointing.

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Interesting. Your answer would make a great comment, but doesn't really answer the question. –  intuited Jul 9 '12 at 18:48

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