NVIDIA has reduced HBM4 memory requirements for its "Rubin" GPUs as SK hynix and Samsung struggle to meet the original 22 TB/s bandwidth target. Initial shipments will achieve closer to 20 TB/s, indicating a setback in NVIDIA's aggressive upgrade plan. The VR200 NVL72 system bandwidth targets grew from 13 TB/s in March 2025 to 20.5 TB/s by September, then 22 TB/s at CES 2026.

Facing supply chain challenges, Micron has exited HBM4 memory production, leaving only SK hynix and Samsung to supply this crucial component. SK hynix will capture approximately 70% of HBM4 supply for VR200 NVL72 systems, with Samsung providing the remaining 30%. This reallocation forces NVIDIA to adjust performance expectations downward from the ambitious 22 TB/s target.

The memory constraints impact NVIDIA's competitive positioning against AMD's Instinct MI455X accelerator, which offers 19.6 TB/s bandwidth. NVIDIA addressed initial bandwidth gaps through faster DRAM and improved interconnects. Micron will now focus on supplying LPDDR5X memory for "Vera" CPUs, offering up to 1.5 TB capacity to compensate for lost HBM4 market share in the VR200 ecosystem.