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

Our community is populated with tons of enthusiasts and many of them are very well skilled in various areas of the computer sciences. Because of that, we thought that the most interesting things that happen on our forums should also be published on the website, so many others can benefit from the experience of our community members. And we are starting this “LAB501 contributors program” with a thorough DIY eGPU implementation from our forum member Arise.


As the need for mobility is on the rise, many users found themselves facing a dilema – should I buy the ultra portable device which I can take anywhere with me, but sacrifice gaming performance, or should I go for a desktop PC which can use a massive graphics card, but which cannot be carried around?

The real question here is… what would you say if I told you that you can have both? An ultraportable device that you can take with you anywhere, that can be connected to some sort of device back home, in order to have desktop like graphics performance… Does such a thing exist? No, but we can build it in the form of an eGPU setup!

There are several ways to connect a video card to a notebook and while the physical connectors and cables can take various forms, at the electrical level there is no difference, it is just a PCI Express link. So far people were able to connect video cards to their computers using mPCI Express slots or PCI Express Cards, however, recently, Thunderbolt became the prefered choice for most new implementations.

So what exactly is this Thunderbolt thing? If we ask Apple they would say something like: ”Thunderbolt is a revolutionary I/O technology that supports high-resolution displays and high-performance data devices through a single, compact port.” Such a definition is kinda exactly what we are looking for when trying to connect a graphics card to a notebook, basically we need a technology that can provide high-performance data devices through a single, compact port.

The original Thunderbolt connector, being built on the miniDisplayPort connector was designed to keep the DisplayPort protocol and add the PCI Express capability, mapping them in a single protocol that can be transmitted over a single cable between Thunderbolt controllers available at each end.


Designed to be a one cable solution for everything that means it needs to have a lot of bandwidth at its disposal. First version of Thunderbolt chipset is capable of providing two full-duplex channels, each channel providing 10Gbps of bi-directional bandwidth. That’s 10 gigabits per second in each direction. In terms of speed, when looking for raw numbers, it is up to 20 times faster than USB 2.0 and up to 12 times faster than FireWire 800. In essence, from the eGPU implementation point of view, Thunderbolt is a muxer/demuxer capable to combine all those signal lanes found on PCI Express boards and send them over a thin and flexible cable.


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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