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Graphics Anyone familiar with external GPUs for laptops?

Discussion in 'Hardware' started by Pete J, 18 Sep 2018.

  1. Pete J

    Pete J Employed scum

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    Hey all,

    I've been wondering about using an ultra portable laptop with external GPU. I have a few questions:

    1) Do they all work with any laptop?
    2) Can a monitor be directly linked to the GPU rather than the laptop?
    3) Can multiple monitor gaming be run on such a setup?
    4) Do any offer the ability to use more than one connection to the laptop to improve bandwidth?

    Thanks in advance!
     
  2. GeorgeK

    GeorgeK Swinging the banhammer Super Moderator

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    https://forums.bit-tech.net/index.p...drives-coolers-ryzen-bundle-projector.349244/

    In this thread @David mentioned that he has moved over to such a setup - hopefully he'll chime in :)

    Edit: Also I read an article (which typically I can't find right now) which said that some laptops are beginning to use multiple thunderbolt(?) connections to increase the bandwidth. IIRC each thunderbolt connection was the equivalent of something like 2 PCIe lanes. I really need to find that article as I might be talking complete b******s

    Edit 2: Found it

    https://egpu.io/ultrabook-buyers-guide-external-gpu/#pcie
     
    Last edited: 18 Sep 2018
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  3. David

    David Take my advice — I’m not using it.

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    1) Do they all work with any laptop?
    No - modern eGPUs require a Thunderbolt 3 connection - meaning full 40Gbps bandwidth.

    2) Can a monitor be directly linked to the GPU rather than the laptop?
    That's how it works - the Laptop connects to the eGPU box vis TB3 and the monitor runs off the GPUs outputs just like it would in a PC.

    You can use an eGPU to accerelate games on the laptop's display, but you're giving up some of the TB3 bandwidth to two-way data transfer.

    3) Can multiple monitor gaming be run on such a setup?
    You're limited to the outputs on the graphics card - remember eGPU enclosures are just boxes that hold and power a standard PCIE graphics card. i.e. I can and have pulled my card out of the box and run it in a regular PC.

    4) Do any offer the ability to use more than one connection to the laptop to improve bandwidth?
    Not seen any yet, but some form of link aggregation is the the next likely step.


    There is a downside to eGPUs: the limits of TB3 and the overheads required mean you don't see the full potential of your card. Mine is an Aorus 1070 Gaming Box and the GTX 1070 in there probably gives the same gaming performance as a GTX 1060 6GB.

    Increased bandwidth in the future will improve this, but it's best to go in with your eyes wide open.

    A lot of TB connectors were limited to two lanes, as you say, but new laptops like my XPS 15 9570 sport TB3 connectors which use all four lanes and 40Gbps. Even that isn't enough to realise the full potential of a high(ish) end GPU, which is why link aggregation is the logical next step - I haven't seen an eGPU that has two TB3 ports and can make use of them in this manner though.

    TB3 is still pretty new - my XPS only has one socket and many that sport several do not all support the full four pcie lanes per link.

     
    Last edited: 18 Sep 2018
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