TechCompare LogoTechCompare

DDR4-3600 CL16 first-word latency is 8.9 ns

DDR4-3600 CL16 is the AM4 sweet spot every Ryzen 3000 / 5000 overclocker converges on — 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.

First-word latency
8.89 ns
CL16 @ 1800 MHz bus
Row cycle time (tRC)
32.2 ns
tRP + tRAS
Peak bandwidth
28.8 GB/s
Per channel

Calculator

RAM Latency Calculator

MT/s
clk
clk
clk
clk

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

Peak bandwidth per channel28.8 GB/s

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

DDR4-3200 CL16
CL16 • 3200 MT/s
View details ➜
DDR4-4000 CL18
CL18 • 4000 MT/s
View details ➜

Frequently asked questions

What's the true latency of DDR5-6000 CL30?
True latency = (CL × 2000) ÷ speed = (30 × 2000) ÷ 6000 = 10 ns. That's one of the fastest mainstream kits currently shipping; most DDR5-6000 kits at stock JEDEC timings sit closer to 13-14 ns.
How do CL and MHz affect RAM speed?
Data rate (MHz) determines how much bandwidth you get; CL determines how long you wait for the first bit. Higher MHz + lower CL = more throughput plus faster access. A kit with twice the MHz and equal CL halves the true latency in nanoseconds.
Is DDR5-6000 CL30 better than DDR4-3600 CL16?
DDR5-6000 CL30 is 10 ns true latency; DDR4-3600 CL16 is 8.9 ns — DDR4 is actually slightly lower latency on that comparison. But DDR5-6000 has nearly 67% more bandwidth, which matters far more for modern CPUs, especially AMD Ryzen 7000/9000 and Intel 12th-gen+.
What are tRCD, tRP, and tRAS?
Secondary timings. tRCD is the delay to activate a row before accessing a column; tRP is the time to close a row before opening another; tRAS is the minimum time a row must stay open. All three are measured in cycles; converting to ns uses the same formula as CL.
Does faster RAM help gaming?
On AMD Ryzen and modern Intel platforms, yes — especially in CPU-bound 1080p titles where the gap between DDR5-5200 CL40 and DDR5-6400 CL32 can be 10-20 fps. At higher resolutions the GPU becomes the bottleneck and RAM speed matters less.
What is JEDEC vs XMP/EXPO?
JEDEC is the default SPD profile every DIMM boots with — conservative timings guaranteed to work anywhere. XMP (Intel) and EXPO (AMD) are overclocking profiles stored on the DIMM that you enable in BIOS to unlock the speeds printed on the heatspreader.

Related tools

Data Read Visualizer

Visualize the massive speed difference between CPU cache, RAM, and storage.

Use tool ➜

Data Transfer Calculator

Estimate transfer times for files over USB, WiFi, Ethernet, and more.

Use tool ➜

WebGPU Benchmark

Stress-test your GPU right in the browser with real WebGPU workloads and get a performance score.

Use tool ➜

Power Cost Estimator

Estimate annual electricity costs for your PC, Server, or TV.

Use tool ➜