“Latency shoots past 400 ns when fighting with five bandwidth threads.”
A Zen 4 desktop idles at 82 to 83 ns of DRAM latency. A single core can pull about 50 GB/s, and a handful of bandwidth-hungry threads on the same CCD push a latency-sensitive thread past 400 ns. Across both CCDs it went beyond 700 ns, while the chip’s own counters averaged about 200 ns. The hardware favours the thread hogging bandwidth, and the performance counters understate the damage.