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A comment on DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix. Parent comment

Re:DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix by extropy on Tuesday October 06, 2020 @01:23PM (#24700222)
At 5ghz, the signals travel only 4 cm each cycle (signal speed in copper is around 60% lightspeed).

Moving stuff further away means waiting multiple cycles for a reply.

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Re:DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix by labawi on Tuesday October 06, 2020 @02:14PM (#24700707)
Random article:

> Power10 chip .. using the DDR4 buffer chip from MicroChip and only adding a mere 10 nanoseconds to memory latency.

At 5GHz that would be 50 cycles or 1m round-trip. The delay is in processing - bridging logical and technical protocols, resynchronization, fanout, probably even a cache layer.

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