USB 3.0 docking station performance / display data rate

Looking toward the purchase of my next laptop computer, I need to decide whether to get one that has a dedicated docking connector, or one that uses USB 3.0. Laptops that use a dedicated connector are increasingly rare, but I have concerns about the bandwidth of USB.

My concern centers mainly on display bandwidth. The major advantage of using a docking station for me is to be able to attach and detach the computer by making or breaking a single connection. This dictates that the monitor(s) be attached to the docking station and receive data through the USB channel.

The theoretical maximum data rate of a USB 3.0 connection is 5.0 Gb/sec; for a DVI connection it is 3.96 Gb/sec. Thus a DVI monitor could, theoretically, eat up most of the docking station's bandwidth. If I attached two monitors, they would (again theoretically) demand nearly twice the available bandwidth.

I know that data channels merely achieve anything approaching their theoretical maximum data rate in the real world, but that applies to USB as well as DVI. So far I haven't been able to find any solid data on real-world DVI data rates, or on actual performance of USB 3.0 docking stations with demanding video operations.

Can anyone refer me to useful sources of information, on either topic?

 

simple, if it is a demanding video application such as gaming, requiring high framerates etc then I find USB docking units very sub par. they are designed great for web browsing, basic video, email etc. I use a couple of them, and are no issue on doing work, or watching 720 video. I have even had flicker running 1080 mkv files on the cheaper one. keep in mind they will also tend to put load on your CPU so make sure you have cycles to spare.

for my needs where I need pretty much the same performance from externals as internal, I still have to rely on the true docks where I can have 2 or 4 external outputs on the PCIe docking channel

but it really all boils down to what do you want to run externally?

AOC USB Monitor for Gaming? - Graphics Cards - Graphics & Displays
USB Docking Station in Review: Fujitsu USB 3.0 Port Replicator PR08 - NotebookCheck.net Reviews

for benchmarks just look up any number of the USB video cards since docks use an internal hub and one of them. and many USB 3 docks are still using USB 2.0 external video on internal port 1

 

Yep, these USB devices don't make use of your dedicated GPU at all, they use their own video processing, so it will be quite weak even compared with the IGP in the CPU.

 

^ What he said.

The Displaylink tech effectively emulates a GPU in software and then slings the frames down the line. A lot of work's been done to offload processing to a present IGP (no discrete GPU assisted acceleration though) but it is still slower than an IGP since it's going [thing which needs to output video] -> [software GPU processing on the CPU] -> [IGP assist] -> [software GPU processing on the CPU] -> [dock out].

Fine for Youtube, but not for >HD. Gaming - unless it's simple stuff, forget it.

 

I'm not a gamer, but this will be my primary computer, and I will use a broad (and somewhat unpredictable) variety of software on it for my work. I use applications like Visio and Photoshop which can be graphically demanding. So I fall into the rather broad gap between "gaming and 3D" and "Facebook and email." It sounds like I'll have to try out one of these devices to find out whether they'd meet my needs, or simply avoid them.

I wonder whether a Thunderbolt dock would change the situation. Thunderbolt isn't widely enough implemented yet to be a realistic alternative, but I can foresee that at some point it will be.

 

Depends on the dock. Thunderbolt is basically PCI-e exposed as a port, so theoretically* it's a lot more useful. Also any display plugged into the Thunderbolt port is capable of being a display to the onboard IGP/GPU, removing that Displaylink bottleneck.

*But if you take Apple as the example, they haven't done anything particularly useful with it - really just as a means of making their hardware more compact and "housewife-friendly".

 

TB docks seem to be almost as bad. atleast the couple I have tried. if you are going to go that way you are still better off to jam a DP/mDP or HDMI cable into the side of your laptop. as a photo/video editor I can also tell you that editing through a dock is not a lot of fun, colors are well known to shift or you wind up spending a lot of time forcing a redraw to get rid of artifacts.

I'm a good housewife and its still a pain in the gluteus maximus. I have relegated mine to being a display port only

 

The displaylink chip do compression iirc, I would't worry about bandwidth if the dock says it support so and so number of monitors.

 

After researching these issues with docking stations last year, I was concerned about the video capabilities so I just put together my own station; I primarily use my laptop with a full size monitor and keyboard.

It only takes three connections to the laptop: HDMI cable for monitor, 7 port usb hub with all the peripherals attached, and the AC adapter. I don't find it takes any significant amount of time to plug the cables in if you keep them organized together. I purchased an extra power adapter to keep under the desk so I don't have to move it.

 

You're lucky you don't have to deal with Ethernet too. I can't wait three minutes for the decent-sized files I work with to load from or save to the network every time I need one or have made a change.


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