Omer Cheema(@Omercheema):Samsung and SK hynix have been building 12-high HBM4 (36 GB) as the default stack for NVIDIA’s Vera Rubin. NVIDIA has asked both suppliers to raise the share of 8-high HBM4 in second-half 2026 shipments, and that HBM4E may also lean 8-high. The stated reasons are thermal headroom, packaging yield, and supply flexibility: HBM4 doubles the I/O width to 2,048 pins versus HBM3E, which raises bandwidth but also heat and power in already dense GPU packages. An 8-high part uses fewer DRAM dies per cube, so more cubes can be produced from the same constrained wafer starts.

2026.08.27 20:26

Samsung and SK hynix have been building 12-high HBM4 (36 GB) as the default stack for NVIDIA’s Vera Rubin. NVIDIA has asked both suppliers to raise the share of 8-high HBM4 in second-half 2026 shipments, and that HBM4E may also lean 8-high. The stated reasons are thermal headroom, packaging yield, and supply flexibility: HBM4 doubles the I/O width to 2,048 pins versus HBM3E, which raises bandwidth but also heat and power in already dense GPU packages. An 8-high part uses fewer DRAM dies per cube, so more cubes can be produced from the same constrained wafer starts.