Its a DGX dev box, for those (not consumers) that will ultimately need to run their code on large DGX clusters where a failure or a ~3% slowdown of training ends up costing tens of thousands of dollars.

That's the use case, not running LLM efficiently, and you can't do that with a RTX5090.

I get the idea. But isn't 128G of "VRAM" (unified actually) could train a usefull ViT model ?

I don't think the 5090 could do that with only 32G of VRAM, couldn't it ?

DGX Spark is not for training, only for inference (FP4).