RAM Sub-Timings, tRFC & Real Nanosecond Latency Calculator
Compute real physical cycle times (ns), primary timings, tRFC refresh stalls, theoretical memory bandwidth (GB/s), and competitive 1% low frame pacing.
โ๏ธ Primary & Secondary TimingsDDR5
Nanosecond Cycle Decomposition
๐ก Sub-Timing Golden Rules for Competitive Gaming
In heavy firefights (like smokes and airstrikes), your GPU streams hundreds of textures through RAM. Default XMP profiles freeze banks for 300ns to 500ns on every refresh. Tightening tRFC cuts these micro-pauses by half.
Extending tREFI from 32,768 to 65,535 or 131,071 gives huge latency benefits, but causes capacitor leakage if memory temps exceed 50ยฐC. Ensure your case has active airflow across the RAM sticks.
Always set tRRDS=4, tRRDL=4, and tFAW=16 on DDR4/DDR5. Leaving tFAW on AUTO (often 32โ48) severely restricts consecutive bank activations.
Frequently Asked Questions
Why is true nanosecond latency more important than just MT/s frequency?
Memory data rate (MT/s) only measures raw throughput bandwidth, while CAS latency (CL) is measured in clock cycles. True access latency in nanoseconds is calculated as (CL ร 2000) รท Data Rate. For example, DDR4-3200 CL14 (8.75ns) actually responds faster for initial memory requests than DDR5-5200 CL40 (15.38ns), even though the DDR5 module has higher raw transfer speed.
What is tRFC and why does it drastically affect 1% low FPS in competitive games?
tRFC (Row Refresh Cycle Time) defines how many clock cycles a DRAM bank remains completely inaccessible while its capacitor cells refresh electrical charge. Because standard XMP profiles set loose safety margins (often 350nsโ500ns), tightening tRFC to 120nsโ160ns (on Samsung B-die or SK Hynix A-die) eliminates micro-stutters and drastically raises 1% and 0.1% low framerates in CPU-bound games like Warzone, CS2, and Valorant.
What is the optimal memory sweet spot for AMD Ryzen 7000 and 9000 (Zen 4 & Zen 5)?
DDR5-6000 with CL30-36-36 or CL28-36-36 running 1:1 FCLK (Memory Controller Clock = DRAM Frequency at 2000MHz/3000MHz) delivers the lowest latency. Exceeding 6000โ6400 MT/s forces the memory controller into a 1:2 divider, adding a 10ns latency penalty that degrades gaming performance unless pushing past 8000 MT/s.
How does tREFI improve memory efficiency?
tREFI (Refresh Interval) determines how long the memory can perform read/write operations before forcing a refresh cycle. Maxing out tREFI (e.g. 65,535 on DDR4 or 131,071 on DDR5) reduces refresh downtime by up to 80%, yielding tangible frame rate stability provided your memory temperatures stay below 50ยฐC.