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

So, cards on the table, what do we need exactly to make a Thunderbolt eGPU implementation? First, we need a notebook with such a Thunderbolt port onboard. There are a couple of notebooks so far that feature a Thunderbolt connector, most of them are Apple’s Air and MacBooks but there are also notebooks from Asus like G750 Series or G46 Series.

Second, we need a Thunderbolt PCI-Express Expansion board. Those are boards with one or more Thundebolt ports at one end and one or more PCI Express Slots that allow adding PCI Express cards. Like a video card. Unfortunatelly , such expansion boards are pretty expensive, but to name a couple, you can look for AKiTiO Thunder2 PCIe Box, ThunderTek/PX PCIe Expansion Chassis, and also several Thunderbolt products from OWC, Magma and Sonnet Technologies.

Third, we need that cable, with length from 50cm to 2 or 3 meters. I’ve found that longer is better, just don’t settle for 50cm just because is cheaper. Having the eGPU far from you is actually a good thing. And at last, we need a Video Graphics Card and some power source to power the card.

So far all seems good, but you may ask why is this a DIY implementation and not a readily available one so anyone can go out and purchase it?

The answer is dead simple. The eGPU project implementations are actively blocked by Intel, Apple and several other companies. The reason behind this is not made clear, however it can be assumed that it has something to to with compatibility issues and also the fact that spreading of such eGPU implementation could become a comercial threat to some sales/business patterns.

In the past Intel used to lockdown the x1, x2, x4 port settings in the flash descriptor region for notebooks equiped with SandyBridge processors and later, and now, both Intel and Apple must approve licenses for Thunderbolt based products. So far they refused granting certifications for Thunderbolt products without a case/enclosure (it means no one can sell only the board) and they are refusing expansions boards with 16x length slots. They also clearly mention in their guidelines regarding Thunderbolt implementations that video cards support is not allowed.

Lastly, Thundebolt is a somewhat complicated technology, hot plug support for PCI Express card was never considered (you don’t think about taking out your video card or sound card from your desktop PC while powered on, right?). Unlike desktop motherboards, notebooks could possible run into some BIOS issues in order to accomodate the video cards in the PCI memory space, so BIOS updates are required (as we know, laptop makers won’t bother much with releasing BIOS versions) or… some applications to do that.

There were some attempts for complete comercial implementations for Thunderbolt based eGPUs from companies like Asus and MSI, but guess what, they never saw the store’s shelves. Intel refused to certificate them.

So, the only thing you can do if you want to connect a powerfull graphic card to your notebook is to attempt a DIY eGPU implementation…

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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