Nvidia Is Testing Rubin Ultra at 192GB and Stepping Back From HBM4E to HBM4 as the Memory Shortage Bites

Tom's Hardware citing TrendForce (corroborated by Seoul Economic Daily), via r/LocalLLaMA (75up/41c)·medium signalXBlueskyLinkedInCopy link

TrendForce reporting relayed by Tom's Hardware says Nvidia is prototyping Rubin Ultra variants with 192GB or 256GB of memory — down from the announced 288GB — and some configurations use fewer than the 16 announced stacks and substitute HBM4 for the originally specified HBM4E. The driver is tightening HBM supply across all three producers (SK hynix, Samsung, Micron); at GTC 2025 configurations up to 1TB of HBM4E were on the table. The practical consequence for anyone planning capacity: a model that fits on four high-memory GPUs may need six or eight lower-memory ones, dragging along more power, rack space, interconnect and licensing.