Is DDR4-3600 CL16 the AM4 sweet spot? Zen 3 performance and timings
DDR4-3600 CL16 is the AM4 sweet spot every Ryzen 3000 / 5000 overclocker converges on. It's the last speed grade where the Infinity Fabric runs 1:1 with memory on most chips, and the point where DDR4 timing tuning gives its biggest practical gains. Its 8.89 ns first-word latency is faster than any stock DDR5 kit below 6000 MT/s.
Calculator
RAM Latency Calculator
Timings are in memory clock cycles. True latency in nanoseconds is derived from the data rate.
True Latency
First-word latency (CL)
8.89 ns
Time from a read command to the first bit of data arriving.
I/O bus clock
1800 MHz
Cycle time
0.556 ns
tRCD delay
10.56 ns
tRP delay
10.56 ns
tRAS
21.67 ns
tRC (tRP + tRAS)
32.22 ns
Assumes one 64-bit channel. Dual channel doubles this, quad channel quadruples it.
How this is calculated
1800 MHz bus clock, 0.556 ns per cycle, 16 cycles of CL = 8.89 ns. Per-channel bandwidth is 28.8 GB/s, tRC is 32.2 ns. On Intel platforms DDR4-3600 CL16 also works well, but the speed advantage over DDR4-3200 is smaller because Intel's ring-bus architecture is less memory-latency-bound than Ryzen's Infinity Fabric.
Verdict
DDR4-3600 CL16 is the only speed grade a Ryzen 3000/5000 AM4 builder should consider if they care about memory performance. It's widely available, universally supported by Zen 2/Zen 3 memory controllers, and measurably faster than DDR4-3200 in the workloads that care.
More DDR4 scenarios
Frequently asked questions
Why is DDR4-3600 CL16 better than DDR4-3200 CL16?
Can all AM4 motherboards run DDR4-3600 CL16?
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