# RAM Timing Memory Latency Calculator | CL to ns | FPS Chaser

Canonical: https://fpschaser.com/ram-timing-memory-latency-calculator/

> Enter DDR frequency and CAS latency, get first-word access time in nanoseconds, CL x 2000 / MHz. Plus Samsung B-Die sub-timing rules for tRFC, tFAW and tREFI.

# RAM Timing & Latency Calculator

Nanosecond Precision Analysis & Samsung B-Die Sub-Timing Rules

### Why Memory Latency Controls 1% Lows

When a game engine encounters a CPU draw call (like an opponent peeking a corner or an explosive grenade detonating), the CPU core must query system RAM. If your memory latency is 65ns instead of 36ns, the core stalls for nearly double the clock cycles, causing an instantaneous frame-time spike (a micro-stutter).

Select Hardware Profile / Benchmark Preset:

### Timing Input Matrix DDR Frequency & Primaries

Memory Frequency: 3600 MT/s (MHz)

2133 MHz 3600 (DDR4) 6000 (DDR5) 8400 MHz

CAS Latency (tCL): 14

CL12 (Extreme B-Die) CL16 CL30 CL44

RAS to CAS Delay (tRCD): 14

Row Precharge (tRP): 14

Row Active Time (tRAS): 34

Refresh Recovery Time (tRFC): 280 cycles
Real recovery: **155.6 ns** (B-Die targets <140ns)

Latency Telemetry REAL-TIME

First Word Access Time: 7.78 ns Formula: (CL × 2000) ÷ MHz

Estimated AIDA64 System Latency: 33.9 ns Includes Ring Bus & Sub-timing overhead

Theoretical Dual-Channel Bandwidth: 57.6 GB/s

Performance Index:
Elite Tier (Zero Micro-Stutter)

### Samsung B-Die & DDR4/DDR5 Sub-Timing Cheat Sheet

Primary timings (CL, tRCD, tRP) represent only ~35% of total memory performance. The remaining 65% of 1% low framerate stabilization comes from secondary and tertiary timings.

| Timing Parameter | Role & Function | Samsung B-Die (Safe) | Tuned (Max FPS) | Golden Rule / Formula |
| --- | --- | --- | --- | --- |
| tRFC | Row Refresh Cycle Time | 300 – 350 | 240 – 280 | Target ~130ns–140ns. Massive 1% low impact. |
| tFAW | Four Activate Window | 24 | 16 | Must equal 4 × tRRD_S (4 × 4 = 16). |
| tRRD_S / tRRD_L | Row-to-Row Delay (Short/Long) | 4 / 6 | 4 / 4 | 4 / 4 on Z390 / Z690 provides optimal queue delivery. |
| tREFI | Refresh Interval | 32767 | 65535 (Max) | Higher = better. Keeps memory open longer without pause. |
| tWR | Write Recovery Time | 16 | 10 – 12 | Directly impacts write bandwidth in open world games. |
| tCWL | CAS Write Latency | Equal to tCL | tCL or tCL - 2 | Allows instant turnaround from read to write operations. |

**Stability Testing Protocol:** Run **TestMem5 (TM5)** with **Anta777 Extreme1** or **Universal2** configuration for at least 3 cycles (approx 90 minutes). Zero errors are required before playing competitive ranked matches.

Memory Latency Lab

## RAM & Memory Tuning FAQs

Deep dive into Samsung B-Die sub-timings, tRFC, tFAW, Gear modes, and memory stability diagnostics.

Ctrl+F

DRAM stores bit charges in microscopic capacitors that leak voltage rapidly. Every few microseconds, the memory controller must refresh all memory rows.

While a row is refreshing (the duration of tRFC), the CPU cannot read or write data to that DRAM bank. Default XMP profiles set tRFC loosely (often 600–800 cycles, or ~350ns).

Samsung B-Die memory can run tRFC down to 260–300 cycles (~130ns–150ns). This cuts bank refresh stall duration in half, eliminating memory-induced frametime hitching in esports.

Key Takeaway:
Tuning tRFC yields the single largest reduction in memory latency and the biggest increase in 1% low framerate.

[Open RAM Timing & Latency Calculator](https://fpschaser.com/ram-timing-memory-latency-calculator/)

Need more details on this optimization layer? [Master Zero-Latency Checklist](https://fpschaser.com/fps-optimization-checklist/)