同じシリコンでも別の製品
HBM (high-bandwidth memory) stacks 8 to 16 DRAM dies with through-silicon vias and bonds them beside a GPU or ASIC. DDR5 and DDR4 are single dies sold into servers, PCs and modules. Both start as DRAM wafers at the same three suppliers, so they compete for the same fab capacity.
HBM は、アクセラレーターの買い手候補の少数のリストに複数四半期の割り当てで販売されます。 DDR5 と DDR4 は契約に基づいてオープン スポット ボードで取引されます。そのため、DDR5 では毎日のスポット プリントが行われるのに対し、ここでは HBM レベルがフラグ付きで報告されるか、サプライチェーン レポートから派生して報告されます。
今日のボードの GB あたりのコスト
HBM3 24GB: $8.31/GB. HBM3E 36GB: $58.56/GB. HBM4 48GB: $73.35/GB. DDR5 16Gb: $29.27/GB. DDR4 16Gb: $41.48/GB. GDDR6 16Gb: $5.81/GB.
These per-GB figures are derived: the published level divided by the part's capacity. The HBM3E and HBM4 levels are scarce-lot spot indications reported in September 2026, several times long-term-agreement pricing, so contract buyers pay materially less per GB than this line suggests. Read the HBM per-GB number as a ceiling, not a typical cost.
HBM の需要が DRAM 価格を上昇させる理由
Each HBM bit uses roughly three times the wafer area of a DDR5 bit once stacking yield and the larger die are counted. Every wafer moved to HBM removes several times its HBM output from the commodity market. Suppliers have been moving wafers because HBM margins are higher, which is the core of the 2025–26 DDR5 and DDR4 squeeze.
The chart rebases every line to 100 so you can see which part moved first. Over longer windows the commodity lines have moved further than HBM: HBM is priced a year ahead under allocation, while spot DRAM reprices every session.
何がギャップを狭めるのか、あるいは広げるのか
Downside first: consumer DRAM demand is soft under current prices, and DDR5 spot inquiries have slowed in September. If spot DRAM stalls while HBM allocation holds, the HBM-to-DDR5 ratio widens again. Extra HBM4 capacity at SK hynix, Samsung and Micron could also ease the scarce-lot HBM premium through 2027.
Upside: any accelerator build-out beyond current allocation keeps converting wafers and holds commodity DRAM tight. Watch a sustained negative 30-day print on HBM3, the oldest generation, as the first sign HBM pricing is softening.