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NVLink is a technology from NVIDIA for creating a high bandwidth link between two compatible video cards. It can be used for many things, from basic SLI for faster gaming to potentially pooling GPU memory for rendering large and complex scenes. What NVLink can be used for depends on how software developers write their applications, and there is a lot of exciting potential for this technology.
However, NVLink requires a physical bridge between the cards in order to enable these capabilities – and NVIDIA isn't transparent as to which models of the NVLink bridge will work with which video cards. Several Quadro video cards support NVLink, along with some of the new GeForce RTX 20-series cards and the Titan RTX. NVLink bridges are available with Quadro or GeForce branding in various sizes.
If you have already set up a system with NVLink, you can find instructions for enabling and testing it on another article.
Here is a chart of all the NVLink compatible video cards, as of publishing time, along with the various NVLink bridges that are available:
|NVLink Bridge →
↓ Video Card
|Quadro GP100||Works (Tested)||Should Work||Does Not Work||Does Not Work||Does Not Work||Does Not Work|
|Quadro GV100||Does Not Work||Works (Design)||Does Not Work||Does Not Work||Does Not Work||Does Not Work|
|Quadro RTX 5000||Does Not Work||Does Not Work||Works (Design)||Does Not Work||Does Not Work||Does Not Work|
|Quadro RTX 6000||Does Not Work||Should Work||Does Not Work||Works (Tested)||Works (Tested)||Should Work|
|Quadro RTX 8000||Does Not Work||Should Work||Does Not Work||Works (Design)||Should Work||Should Work|
|Titan RTX||Does Not Work||Should Work||Does Not Work||Works (Tested)||Works (Tested)||Works (Design)|
|GeForce RTX 2080||Does Not Work||Should Work||Does Not Work||Works (Tested)||Works (Tested)||Should Work|
|GeForce RTX 2080 Ti||Does Not Work||Should Work||Does Not Work||Works (Tested)||Works (Tested)||Should Work|
For the combinations indicated as "Works", we specified whether we have actually tested it or it is just assumed to work because NVIDIA designed it to. For example, the Quadro 6000 RTX NVLink Bridge is clearly designed to work on the Quadro RTX 6000, as well as the upcoming 8000 – but we only have RTX 6000s in-house to test currently. Likewise, the RTX 5000 has its own bridge designed for its smaller NVLink connector – so it should work, by design. "Should Work" indications are used where we believe the combination will work based on other testing we have done, but we don't have samples on hand to verify for sure. "Does Not Work" should be self explanatory.
The main takeaways from our testing are as follows:
- The older Quadro GP100 cards were equipped with the first generation of NVLink, and had less bandwidth per link than newer models. As such, the Quadro GP100 bridges do not work with newer cards.
- The Quadro GV100 cards use the second generation of NVLink, and like the GP100 have two NVLink connectors per card. The newer RTX series bridges can fit on one set of connectors, but their plastic housings are physically larger and cannot be paired up to fully connect both sets of NVLink connectors. That means newer RTX bridges won't fully work on GP100 or GV100 cards.
- Quadro RTX 5000 cards have a smaller NVLink connector than all the other cards, requiring a completely separate set of NVLink bridges. Because of this they do not interchange with any of the other existing video cards, whether RTX generation or older. This seems to be a design decision by NVIDIA, but is strange since the GeForce RTX 2080 has the same lower NVLink bandwidth (50 GB/s total, versus 100 GB/s on the RTX 6000, 2080 Ti, and Titan RTX) but uses the same full-length connector.
- Quadro RTX 6000 and GeForce RTX NVLink bridges may look different on the outside, but they appear to be functionally identical. We've tested both types and found they work across most Quadro, Titan, and GeForce cards in this generation. We cannot yet verify that on the Quadro RTX 8000, because they are not yet shipping, but we have tested on a pair of RTX 6000s and all four bridge variants work. Likewise, we have tested them on GeForce RTX 2080, 2080 Ti, and Titan RTX successfully.
- It is worth noting, however, that the LED logo on GeForce RTX bridges does not light up when used on Quadro RTX cards. The Titan RTX bridges also appear to have a NVIDIA logo, but as we don't have them in hand I am not sure if it lights up.
The good news here is that, if you are using hardware from the RTX generation – except for the Quadro RTX 5000 – it looks like you can use a GeForce, Titan, or Quadro branded bridge without needing to worry about compatibility. That is particularly helpful since they come in different sizes: 2- and 3-slot for Quadro and 3- and 4-slot for GeForce / Titan. I'm not sure why NVIDIA didn't just make 2-, 3-, and 4-slot solutions that were brand agnostic… but at least there don't seem to be any weird limitations on which bridges work with which cards. They are also all the same price, as of publishing time, if purchased directly from NVIDIA. The older GP100 and GV100 are a different story, and if you are using those you should just stick with the paired bridges built for each model, respectively.
If you want more info about NVLink in Windows, check out another article we published on the topic.
If you need a walk through on enabling NVLink in Windows, or want to make sure it is work, we have an article covering those topics too.
If you are interested in NVLink, Linux, and machine learning, check out Dr Kinghorn's HPC Blog.
For a list of all articles where we've talked about NVLink, use our website's search function.