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External Graphics Performance: GPU Compute

Echo Express Pro: Desktop Graphics In A Thunderbolt Chassis
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Sonnet Technologies' chassis wasn't designed for graphics cards. It doesn't expose six- or eight-pin auxiliary power connectors. So, you either need to use entry-level graphics hardware like the Radeon HD 7750, or be willing to run a couple of leads from your PC's power supply. Naturally, that doesn't map over to notebooks, but it still makes for an interesting experiment.

Although we know what the Echo Express Pro was meant to do (enabling performance-oriented expansion for storage, A/V, networking, and so one), dropping a graphics card into the enclosure is way cooler. Most of our excitement stems from the fact that notebook graphics potential is highly dependent on the thermal, mechanical, and electrical constraints of a mobile platform. Taking that outside of the box, so to speak, opens the door to more flexible configurations.

Nowadays gaming isn't the only application for GPUs, though. The breadth of GPU-accelerated software is widening, including compression algorithms, video editing, image editing, and even bitcoin mining. Many of these titles are able to fully utilize a graphics processor's resources, consequently putting more stress on the interconnects linking each subsystem. How big of an impact does externalizing a four-lane PCI Express link have on compute performance?

CLBenchmark is a new tool created by our friends at Kishonti, also known for their GLBenchmark program for iOS and Android. It is similar to LuxMark in that it can test ray tracing and image manipulation; however, we are specifically focusing on its SPH Fluid Simulation benchmark.

As you'd expect, the card plugged straight into a motherboard performs better. But the magnitude of the impact depends on the GPU's performance, it seems. AMD's Radeon HD 6970 runs 14% faster plugged straight in to a 16-lane PCI Express slot, whereas Nvidia's GeForce GTX 460 is only 5% faster. If you're looking to upgrade a notebook with mainstream card without auxiliary power connectors, it's probable that Thunderbolt won't negatively affect its potential much at all.

LuxMark tells us a similar story. The Radeon HD 6970 takes a much larger hit than Nvidia's GeForce GTX 460. The 6970 is not particularly realistic in this application, though, given its power requirements. Boards with more conservative power needs should perform almost as if they were running in a native x16 slot, even if you attach them via Thunderbolt using Sonnet Technologies' chassis.

Diagnostics like SiSoftware's Sandra specialize in isolating specific subsystems. This title's general-purpose processing module effectively factors out interface bandwidth as a variable, putting most of its emphasis on the GPU. As a result, it doesn't really matter if you operate over a native 16-lane link or Thunderbolt's 10 Gb/s channel.

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  • 24 Hide
    amuffin , September 17, 2012 5:04 AM
    Well, getting a laptop that supports thunderbolt is already pretty expensive. Then, you have to get one of these which ranges from $400-$800. THEN you have to buy a dedicated card....

    It's pretty expensive once you add it all up :/ 
Other Comments
  • 24 Hide
    amuffin , September 17, 2012 5:04 AM
    Well, getting a laptop that supports thunderbolt is already pretty expensive. Then, you have to get one of these which ranges from $400-$800. THEN you have to buy a dedicated card....

    It's pretty expensive once you add it all up :/ 
  • 2 Hide
    yobobjm , September 17, 2012 5:04 AM
    I like it, but I see limited use for it, especially for those of us who already have large towers, and don't really want another small tower added on to that. That being said, this would make a pretty awesome home dock for a laptop, and good for those tiny desktops that intel, apple, asrock, zotac and many others make (once all of those get thunderbolt).
  • 6 Hide
    acku , September 17, 2012 5:06 AM
    Prices will go down. Remember that.

    Second, it's about the cost you'd have to pay anyways for a desktop (which you need if you want to game since you can't on a vanilla ultrabook), so its more like an alternative solution for those who want a single system setup.

    Cheers,
    Andrew Ku
    Tom's Hardware
  • 4 Hide
    amuffin , September 17, 2012 5:31 AM
    Quote:
    Prices will go down. Remember that.


    They don't go down enough...
  • 2 Hide
    mayankleoboy1 , September 17, 2012 5:33 AM
    any controller + the surrounding ecosystem that is this expensive cant survive much. Not being a hater, but being a realist.
  • 6 Hide
    acku , September 17, 2012 6:23 AM
    You don't know that :) . USB 3.0 was expensive when it first came out. Look at things now. Wow things have changed. Prices are substantially lower now.
  • 6 Hide
    Darkerson , September 17, 2012 6:51 AM
    Pretty interesting, even with the currently high price tag.
  • -1 Hide
    Vorador2 , September 17, 2012 7:56 AM
    Needs to be cheaper. That's my only serious gripe.

    And well, for this purpose Thunderbolt still needs to be faster to fully take advantage of the external GPU, best around 16 Gb/s since it's the speed of a 16x PCIE 3.0 slot.

    Although you could potentially sidestep this issue if you use two linked thunderbolt interfaces, but then there's the problem of synchronizing data transfers (and finding a laptop with two thunderbolt interfaces...if there's any)
  • 5 Hide
    Menigmand , September 17, 2012 8:04 AM
    If they can make this much cheaper, I would be very interested. I prefer to game on a laptop so I can easily stow it away when I have guests over and need the dining table. An extra box would be ok, as long as it doesn't need an external display.
  • 1 Hide
    assasin32 , September 17, 2012 8:18 AM
    Well this makes things more interesting, when the price goes down and becomes resonable within probably the next few years it may give us the ability to buy laptops and attach some reasonble GPU's to them so we can play games on them a lot better.

    If this was around 8 years ago I would have been all over it and had it for my laptop since I used to use that for gaming.
  • 0 Hide
    beavermml , September 17, 2012 9:00 AM
    this maybe a stupid problem.. but will there be mouse lag using external dock with xtra latency? i dont know internal stuff much...
  • 0 Hide
    de5_Roy , September 17, 2012 11:16 AM
    intel core i5 2400 does not have intel hd 3000 igpu. it has intel hd2000 igpu. iirc core i5 2405s has hd3000 igpu.
  • 1 Hide
    abhijitkalyane , September 17, 2012 12:14 PM
    Think of the possibilities - Sonnet or nVidia or AMD could release Thunderbolt GPUs directly (instead of dock+GPU) - that would be a very viable alternative for Ultrabook gamers.
    If such a combination (UB with i7 + Thunderbolt GPU) is available at a reasonable price, a lot of mobile gamers will consider it. I know I would.
  • -1 Hide
    ojas , September 17, 2012 12:32 PM
    Yeah, but can it play Crysis?

    :p 
  • 0 Hide
    fbbam , September 17, 2012 1:28 PM
    Awesome, but still out of reach for most
  • 0 Hide
    toddybody , September 17, 2012 1:34 PM
    Really cool idea...but the real world application doesnt make much sense for a windows (HW) user. For this much money...you could just build another rig/upgrade desktop internals.

    If gaming on OSX is your cup o' tea...then it does have some (albeit expensive) application.

    No offense, but hardcore gamer + Apple dont jive. Im at peace with the fact my MBA cant game...its great at what it does. Same goes for my gaming desktop (I dont cry about the lost potential of OSX applications on it).
  • 0 Hide
    gunbust3r , September 17, 2012 1:46 PM
    Well, now we know why the Lucid Logic demo is only using a Radeon 6700...
  • 0 Hide
    thefizzle656 , September 17, 2012 2:43 PM
    menigmandIf they can make this much cheaper, I would be very interested. I prefer to game on a laptop so I can easily stow it away when I have guests over and need the dining table. An extra box would be ok, as long as it doesn't need an external display.


    I'm pretty sure that this and all other possible external GPU solutions require an external monitor. The box hooks up the TB port on your computer, and then you have to hook up the actual GPU to a monitor (via HDMI, DVI, etc).
  • 1 Hide
    Anonymous , September 17, 2012 2:56 PM
    Hi there, from reading this review, i noticed that you used it with your macbook pro. Were you able to use the external graphic card with OSX or did you install windows on your mac to use it. Would be really nice to be able to use this in OSX. Also would the Echo express be able to accommodate the GTX 460 or even better hd 7750, or would i need the more expensive echo express pro. Thanks for helping me with these questions. =)
  • 0 Hide
    xenol , September 17, 2012 3:04 PM
    Call me crazy, but maybe this will simplify the laptop market a little (sort of). At least in the entry level to midrange, the only thing distinguishing laptops is their processor, memory, storage, etc. Then if the user wants to, add in a discrete external card.

    Should also save board space since you no longer have to have a dedicated GPU and its RAM and house keeping to put on the board. Which means more room for the battery.
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