Final Tested & Confirmed Working Profile
This document contains the fully validated RAM configuration for running 128 GB DDR5 at 6000 MT/s with UCLK=MEMCLK (1:1) on the MSI MAG X870E Tomahawk using a Ryzen 9950X3D.
These settings avoid training failures (A6 / A64), ensure stability under load, and deliver the best bandwidth achievable on your specific IMC.
Primary Timings (Stable & Tested)
tCL = 42
tRCDWR = 44
tRCDRD = 44
tRP = 44
tRAS = 90
tRC = 132
These are the optimal primaries for your IMC + 128 GB capacity at 6000 MT/s.
Refresh Timings (Leave on AUTO except tREFI)
tRFC1 = Auto (≈1228)
tRFC2 = Auto (≈659)
tRFCsb = Auto (≈569)
tREFI = 65535 T
Attempts to lower tRFC on your IMC did not produce higher bandwidth and caused training failures.
For your chip, Auto values are optimal.
Voltage Settings (Required for Stability)
DRAM VDD = 1.35 V
DRAM VDDQ = 1.35 V
CPU VDDIO = 1.15 V
SoC Voltage = 1.20 V
These values were critical in eliminating A64 and A6 training failures.
Memory Controller / Fabric Settings
UCLK = MEMCLK (1:1 / DIV1 Mode)
Gear Down Mode = Disabled
Command Rate = 2T (auto when GDM is disabled)
Memory Context Restore = Disabled
These ensure full bandwidth and correct IMC operation.
Without these, bandwidth is capped at ~52 GB/s due to 1:2 UCLK.
Notes
- This configuration is the best stable performance profile for your specific IMC.
- Lower timing attempts that included tighter refresh timings (tRFC1 < 1200) resulted in A6 boot failures.
- These settings deliver full stability for:
- workstation loads
- gaming
- 24/7 operation
- high memory throughput
- Safe for long-term daily use.