[News] NVIDIA’s Memory Shake-Up: Rubin Ultra Rethinks 12-Hi HBM4E for 8-Hi HBM4, Rubin GPU Bandwidth Cut 13%

What happened

According to ZDNet, Samsung and SK hynix are preparing to ship 8-Hi HBM4 for Rubin Ultra in 2Q27, departing from the original 12-Hi HBM4E plan; 8-Hi HBM4 was initially absent from NVIDIA's plans, but talks gained traction in 3Q26. The source cites thermal challenges and lower yields in 12-Hi stacks, potentially easing supply constraints. Although both Samsung and SK hynix have completed NVIDIA's qualification for 12-Hi HBM4, their 8-Hi products require separate certification; a source said NVIDIA is expected to deploy both 8-Hi HBM4 and 8-Hi HBM4E in Rubin Ultra-based NVL rack-scale systems depending on rack configuration. TrendForce says 8-Hi configurations use fewer DRAM dies, lowering cost per stack and GPU bill of materials, and given tight HBM supply, 8-Hi setups are expected to be a priority for evaluation by many GPU and ASIC vendors in 2027; ZDNet reports 12-Hi HBM4 remains mainstream in 2026, with 8-Hi adoption expected to rise sharply from mid-2027. Economy Tribune, citing Daishin Securities, suggests Anthropic's in-house AI chip could also feature 8-Hi HBM4, raising the prospect of Samsung supplying both foundry services and memory. Separately, per Wccftech, NVIDIA trimmed Vera Rubin's HBM4 bandwidth specifications: an archived September 1 version listed the Vera Rubin NVL72 system with 20.7 TB of HBM4 capacity and 1,580 TB/s bandwidth, the Vera Rubin Superchip at 576 GB and 44 TB/s, and each Rubin GPU at 288 GB and 22 TB/s; NVIDIA has since lowered per-GPU HBM4 bandwidth to 19.2 TB/s and NVLink 6 throughput from the originally advertised 3.6 TB/s to 3 TB/s, cuts of roughly 13% and 17% respectively, and up to 26% for HGX Rubin NVL8 systems, with changes dating back to September. IT Home notes NVIDIA revised the Vera CPU memory specification from a fixed 1.5 TB of LPDDR5X per chip to 'up to 1.5 TB', and that lowering bandwidth requirements could allow more HBM4 products to qualify for Rubin GPUs, potentially boosting overall production output.

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Source: TrendForce · 10/26/2026 · View original source