NVIDIA Rubin Ultra Downgraded: How Much Does This Impact AI Training?

I spent two days running simulations to see how much impact NVIDIA Rubin Ultra's HBM configuration adjustments would actually have on real-world training scenarios. Bottom line up front: For the vast majority of teams, the downgraded 384GB/GPU is still sufficient. The ones who will really suffer are those trying to cram trillion-parameter models onto a single card—but then again, that scenario wasn't meant to be solved by a single GPU anyway.