eGPU – Connecting an external video card to a notebook (DIY implementation)

First thing, like already mentioned on the previous page, we need a notebook with Thunderbolt support. We are going to use an Asus ROG notebook from G750 series, a 17 inch gaming machine, featuring an Intel Haswell i7 4700HQ CPU and a discrete graphics card like Nvidia 765m.


Asus G750JW model features a Cactus Ridge DSL3310 Thunderbolt chipset, capable to power a single Thunderbolt connection port. For the PCI Express Expansion board, I’ve opted (at that time) for a Sonnet Echo Express SE.


It comes in an aluminium enclosure and is bundled with a 12V adapter to provide up to 60W of power for the Thunderbolt chip inside and for the PCI Express card that should be installed.


The Sonnet Echo Express SE solution is based on two boards, a daugherboard featuring a PCI Express slot with a 8x width and the main board with the Thunderbolt chipset soldered on it.




While the PCI Express slot/socket should allow one half-length (up to 6.6″ long), single-width, full-height x8 PCIe 2.0 card, the electrical connection is limited to a x4 PCIe 2.0 (because the actual electrical bandwidth of Thunderbolt is x4). The slot is not allowing us to install a full length x16 board like a modern video card, because the end of the slot is closed. Such an issue can be avoided by using a PCI Express riser, or using some tool like a sharp knife to carve in the plastic to make the card slide in properly.

Hey! Told you this is a DIY project, right?

7 comments la: eGPU – Connecting an external video card to a notebook (DIY implementation)

    1. So you left out the most important information, the penalty of thunderbolt/usb3 and the memory buffering. The most important reasons you see few/no such implementations in the wild.

    2. Compared to desktop, yes. Compared to the dGPU in the laptop…you can see the graphs…

    3. Awesome stuff Monstru! Like it 🙂 Now I want to attach this to my MacBook Pro Retina and do some 3k gaming on it 😀

    4. Glad you like it, I hope it helps a lot of users 😀

    5. Great work!!! Would it be possible to run the pcie with a powered riser? The Sonnet Board needs still be powered, right? Possible to power it through PSU? Thanks

    6. Joseph wrote on:

      I don’t know whether or not I should be posting this here, but I’m having a problem with an egpu unit, when ever I attatch it to my laptop and boot up (either with or without the drivers) my laptop screen on boot up goes to a GPU fail screen (multicoloured and pixelated). I’ve yet to find anyone else with the same problem and from my testing I’ve yet to find a solution :'( .

      If anybody could help me solve this problem I would be over the moon 🙂

    7. What a great explanation. Thanks! From the moment I saw the bandwidth of thunderbolt I knew this would be possible and I am sure there is a commercial market for it. Meanwhile, hopefully more and more enclosures come out with boards which can help make this easier still.

      …and sure, it won’t beat a desktop with the same GPU, but it gives you the chance to have an ultra portable with desktop class graphics which is also upgradable! Brilliant!


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