The following write-up is my experiences for some little known nuances which in the future can be a surprise which can make your computer date much quicker than you intended, with it not being able to handle some of the future devices which will be coming out to the Universal Serial Bus 3.0 Specification.
Many devices you buy now use the Universal Serial Bus (USB) 2.0 Standard and plug – keyboards, mice and even Hard Drive docks. It’s built to give a variety of gadgetry to be able to talk to your computer in a standard way. USB 3 Is a newer standard offered to give much more room for the neat future devices that need it.
The common item to think of when wanting to use USB 3 is for Hard drives – you will be able to copy files much faster to and from it with a USB 3 Device. Let’s backtrack briefly to find out the different kinds of USB 3 that exists in order to try and find out what went wrong.
It began on a bus
Typically, a device had multiple modes of USB that it could implement. In the beginning, it was easy where there was Version 1.1 of the spec being the first mainstream one used. It offered a Low (1.5MBit) and High (12MBit/s) speeds. That sounds pretty obvious which one is which.
The next version arrived in 2000, with Version 2.0 offering 12MBit/s as well as the higher speed of 480Mbit/s.
The cheap way to sell speed
Things were going well with USB 2.0, with both modes giving cheap and speedy access at the time. The higher speed mode was well desired, however manufacturers of gadgets didn’t want to need to retool – so they used the labels of full-speed, and hi-speed. Lets have a look at one of them:
Oh great, I like that one, lets get devices that use the higher speed method right? Actually, that’s the lower speed one. “Full-speed” is the version you are looking for to have the higher 480MBit/s transfer speed.
To make things even more confusing, These labels were both under the 2.0 Spec – USB 2.0 Hi-Speed versus USB 2.0 Full speed. Even while writing this, I needed to double check which one was actually the faster one due to the vagueness in their naming.
Making marketing moves at a low level like this should not be done in order to both allow the consumer make the right decision, as well as give an idea of the meaning of what it actually represents.
(Reference for more information about the USB 2.0 labelling incident available at arstechnica)
In effect, the marketing team made it confusing on what each version was, making both of them sound like the faster version. It’s like wanting a Pony and then realising it’s a straw stuffed imitation that’ll fall apart – nice going guys.
The dark side of USB 3
Looking at the Wiki article on USB 3, It’s main goal was to be offer a transfer rate of 5Gbit/s. This is great, where there is plenty of growth and speed improvements given in this technology. Unfortunately the implementation of this technology appears to have also been clouded – in a different way to the labelling issue with USB 2, we now have the real problem of not being able to find out what true speed we are getting without trying it once you’ve purchased your new computer.
We’ve established the problems with USB 2.0’s release, and we have shown there is a potential problem with the newer version. Are there any examples of it being misleading already? You betcha.
Drawing from personal experience, I ordered an Zotac H55 ITX CE Motherboard. Among other things, it offered speedy USB 3, as seen by this press release:
Two USB 3.0 ports enable the ZOTAC H55-ITX WiFi (H55ITX-C-E) to support the latest SuperSpeed USB devices. USB 3.0 is capable of speeds up to 5 Gbps for 10x the performance of USB 2.0 for external expansion that matches the performance of internal devices.
- Source: Zotac Press release
The term super speed USB 3 means it works at the full rate of around 5gbp/s.
However in practice, this is not the case, with the motherboard running it’s USB 3 ports with a shared total bandwidth between the two ports of 2.5gbp/s.
The Gigabyte H55n Motherboard also promises 5gbp/s operation, as seen in this promotion.
In practice, this is also potentially misleading. When using the integrated graphics of the CPU, More bandwidth is assigned to the USB 3 Port, giving you the full speed.
When you plug in a discrete graphics card however, the bandwidth is then assigned to the graphics card, with the USB 3 port again having a shared total bandwidth available of 2.5gbp/s. This is not user definable in the bios.
All of the reviews mentioned and listed benchmarks showing the USB 3 Ports performing quicker using a USB 3 harddrive. This is a nice feature to know of seeing as its the most common use for the port at the moment. However, it is not an accurate reflection of how the USB 3 is actually allowed to work in your pc, and could cripple the port.
Why is USB 3 Super Speed a sham?
When your computer communicates with your USB 3.0 Port, it will be doing it by interfacing using your computers PCI Express interface. You may have heard of this more commonly when you buy a graphics card, where it’ll be mentioned that it works at 16x PCIe speed. This gives your graphics card an enormous amount of room for it to talk to your CPU and use it to give you the High Definition visuals you are used to.
A single PCIe lane means you will have 2.5Gbit/s available to you – a decent rate. To be able to offer USB 3 at its intended specification of 5Gbit/s.
Laptop manufacturers will often connect only one lane to their USB 3 Chipset. This means that the port will be running at half the rate it should be, and you have no way to find this out.
To make things more confusing, There are three versions of PCIe too – 1x, 2x and 3x. Each one works at double the speed of the previous version.
Devices that make use of USB 3
Now that we know that USB3 Based mechanical hard drives do not max a crippled USB 3 Port, and an expensive SSD can have it’s connection be the bottleneck, what else can?
The original reason I have learned all of these nuances of how USB 3 is being used is that I wanted to use a great capture card from black magic design known as the Intensity Shuttle. These devices offer uncompressed HDMI Capture of other computers or even video game consoles, which is perfect for my needs. Due to the raw bandwidth needed in processing massively sized frames at a high rate, it will actually use the full potential of an USB 3 Super Speed port. This is where the cracks begin to show in current USB 3 Devices.
Although lightpeak may have stolen usb 3’s thunder, Small Raid devices will also take advantage of the higher possible throughput of multiple devices.
Higher throughput cameras may also choose to use USB 3 as well – the current maximum rate a good webcam can transmit data is around 1280 x 720p, using the admittedly efficient UVC encoding method. With the USB 3 standard, It’ll offer another alternative possibly to Firewire, and in the future Thunderbolt
Notable hardware which is known to restrict your USB 3 Speed
Besides the Gigabyte H55n , Zotac H55CE-ITX Motherboards, some common chipsets I have found will have problems
- H55/P55 Chipset based motherboards which use a Intel 1155 Socket CPU have the potential to support fullspeed USB 3, however almost none do, opting instead to most lanes for the PCIe Graphics card.
- Sandybridge based motherboards (H67, P67, Z68) Have the same amount of PCIe lanes as the previous 1155 Socket generation, therefore will suffer the same problems.
- Intel X58 based motherboards have 40 PCIe Lanes available and have native support for USB3. All boards will support Full Speed USB 3.
The future of things to come
It will take awareness that the USB 3 Specification can be crippled depending on how your computer uses the actual port, and labelling is not provided to warn you if the machine is actually providing the lower speed.
Current workarounds are available; You can buy a USB 3 Card, and plug it into an available 4x PCIe v1 or 1x PCIe V2 slot of your desktop. This is far from ideal, as its an extra cost, and not an option on an laptop which will have no ports available.
Some Laptops do have an available Expresscard slot which use an PCIe lane – however it will require support of Expresscard v2.0 on top of an USB 3 slot in card which takes advantage of the specification. The specification itself essentially requires the laptop maker to assign 5gbit/s of bandwidth to it, which will be enough to power one super speed USB 3 port.
On top of all of this, Light peak which eventually became known as Thunderbolt is essentially an 10gbps PCIe port, and has potential to have an adaptor to allow us to forget all the problems with the USB 3 speed issues. If you have a Thunderbolt port though, will you really need to care about USB 3 at all? Until more devices come out with an thunderbolt interface, that will be yes.
Be careful buying a computer, laptop or motherboard with USB 3.0 port. Many of them internally will use a lower speed connection preventing it from doing Super Speed and you may find in the future it will be a bottleneck. As of writing there isn’t an easy way to determine if a machine can truly do the Super Speed implementation.