In academia it's also because NVidia does a lot of stuff to make your life easy.

For example, NVidia came to our University in the UK and provided training for £20 an academic/PhD student for a 2 day course on how to use CUDA and with performance tips, hands on porting of code, etc. They also give away CUDA cards to academics under a hardware grant scheme, so it's possible to get a free Titan Xp this year for a research group.

There's not really an equivalent for AMD or Intel; a Xeon Phi Knights Landing chip is significantly more expensive than a consumer level GPU, and the same cost as a workstation GPU, and it's a lot harder to get good performance from it. It also doesn't seem like AMD are targeting this market, at least not currently.

The main problem is that NVidia is screwing things up. NVidia is only supporting OpenCL1.1, which means that if you want to use C++ / SPIR, you pretty much are locked to AMD / Intel (Intel CPUs have an OpenCL -> AVX layer, so you can always "worst-case" turn OpenCL code into native CPU code)

NVidia of course owns CUDA, which means they want those "premium features" locked to CUDA-only.

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AMD's laptop offerings offer some intriguing features on OpenCL as well. Since their APUs have a CPU AND a GPU on the same die, the data-transfer between CPU / GPU on the AMD APUs (ie: an A10 laptop chip) is absurdly fast. Like, they share L2 cache IIRC, so the data doesn't even hit main-memory, or even leave the chip.

But there's basically no point optimizing for that architecture, as far as I can tell anyway.

Another example would be with Vulkan I guess.

NVidia has lots of models with DX 12 level support that don't have Vulkan drivers.