Why the 512GB M5 Ultra costs so much: 64 RAM channels need custom 8GB chips — two 256GB units may beat one
kingslyj · x · 2026-10-30
junsong explains the pricing of the 512GB M5 Ultra: the chip has 64 RAM channels, and the 256GB model stacks standard 4GB LPDDR5X chips per channel, while hitting 512GB requires custom ultra-dense 8GB chips per channel — that special RAM drives the price. His takeaway: for most buyers, two 256GB machines linked via Thunderbolt 5 (120Gb/s, 15GB/s) cost less, roughly double total memory bandwidth when clustered, and can still run two smaller models separately. migueldeicaza quips that some just wanted the RAM to run Slack and VSCode, not a small AI lab.
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