I'm not an expert and I only have surface knowledge about Oc'ing Dram, for the past 6 years, I've been running 3200mhz with Ryzen 5 3600 with fairly tight timings with 2x8Gig and recently decided to get the exact same kit again to get upto 32GB and I really had the itch to overclock dram, and get the most out of AM4. And I managed to get it running at 3400mhz with these timings above in the screenshot, couldn't get it stable with older timings at 3200mhz. I guess they were just too tight for 4 sticks. So I pretty much copied these timings from a reddit post, because they were running the same mobo and stick combo with 4 sticks which I know are much hard to get stable with daisy chain mbo's, but I couldn't get to 3666mhz like u/Nice_Knee_1538 in that post was able to, 3400mhz was max and stable at 1.405v with these timings above. I started at 1.5v and reduced the voltage till it was unstable.
I also had 5500x3d arriving in the mail and I was hoping I could hit higher frequency with it because it's a newer processor with potential better memory controller etc and also because the person in the reddit post was using a 5600x so I thought it could only get better with the 5500x3d but I wasn't able to post with anything higher than 3200mhz with exact same timings, at 3266, system would not boot, and cmos had to be cleared to get it to boot again. One thing to note tho, I don't understand what VDDCR SOC, CCD, IOD, CLDO VDDP voltages mean and I always left them on auto, only changing the Dram Voltage so I don't know if changing those would help and to what value. I guess I'm just really confused as to why I can't hit 3400mhz with 5500x3d when I was able to get it running with ryzen 5 3600. And I know x3d cpu's dont really benefit from mem oc but I just wanna see a higher number lol and I've been having more fun tweaking the system rather than playing games on it lately so.
System specs
CPU: Ryzen 5 5500x3d
Ram: Gskill f4-3200c14-8GFX 4x8Gb
GPU: Radeon 9070
Mobo: Strix b350-f gaming, latest Bios at the time of writing 6254