Can't get C8HW + 5800x fclk to 1900

[zomgugoff]

C8HW BIOS 3003
5800x
4x8GB 4000 CL18 RAM (CWM32GX4M4Z4000C18)

I cannot get past a F7 qcode at 1900 fclk. It will boot at 1866 but no higher. I've used the safe settings from the DRAM Calculator including the voltages. Is there a guide or any known settings that I need to get 1900 fclk?

[Silent_Scone]

It is important to note that, even with improvements over last gen, not all 5000 series CPUs will reach 1900FCLK unconditionally. You can try adjust VSOC to around 1.15v and try VDDG around 1 to 1.05 and CCD 0.98 - 1.05.

[Baio73]

I don't have a Zen3 CPU, mine is a 3900XT but I can tell how I reached 1900 IF 1:1 with 4x8Gb RAM.
Setting BIOS as suggested by Calculator gave me great instability and reboot problems, so I put all BIOS values to Auto, then set D.O.C.P. (rebooted).
Set RAM speed to 3800, IF to 1900 and bumped voltages (VDRAM 1.48 (mine are Samsung B-Die), VSOC 1.125, VDDG CCD and IOD 1.075, CLDO 1.050). Rebooted.
RAM timings were higher than D.O.C.P., tested to see if it was stable.
Then I took Calculator values and lowered the first till I got errors, then passed to the next one.
Comparing timings with Calculator, I had to raise tRAS form 34 to 37, tRC 52 >54 tWTRL 12>14, tWR 24>25. Lowered tWRWR from 7 to 6 and tRDRD SD 5 to 4.
Other differences werein Termination Block (procODT 36.9 inestead of 48, RTT_WR RZQ/3 instead of OFF, RTT_PARK RZQ/1 instead of RZQ/5).

Hope it helps!

Baio

[RedSector73]

DOCP, SOC Voltage try 1.05, 1.125, 1.1 and see how it goes.

[Kelutrel]

I have a C8F and a 5900X and got to 1900fclk stable using:
DRAM Voltage: 1.4
SOC Voltage: 1.1
VDDG CCD Voltage: 1.05
VDDG IOD Voltage: 1.05
CLDO VDDP Voltage: 0.95
These values were suggested by the DRAM Calculator for Ryzen utility, and did the trick.