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Mismatched DDR4 timings?

thexchange
Level 7
Hello.

Have a question regarding some RAM timings, am trying to narrow down my instability problem once again. For certain third tier, RTL and IOL settings, I see CHA has values that don't match with the rest, whether using the base clock or either one of the XMP profiles. For example, XMP 2 (2800MHz) gives me these:

tRWDR2 - CHA has value 7, the rest has value 6
tRWDD - CHA has value 7, the rest has value 6
tRWSR2 - CHA has value 6, the rest has value 5

RTL - CHA D0 R0 has value 61, CHA D0 R1 has value 59
IOL - CHA D0 R0 has value 8, CHA D0 R1 has value 6

Using base clock, all RTL and IOL values will match, but not the other 3 settings. The rest of the settings are often similar to each other, so these ones easily stand out. Pardon my ignorance, never tried major RAM tweaks before, so can't tell how significant these settings are. RAM just works for older rigs but not this one. I am now on my second board and RAM kit, same type as before: CMK32GX4M4A2666C16. Am I correct that this should not occur? Is the board or processor at fault here, another RMA for the RVE? Should I try a different method, or is another round of testing needed? Or just plain SOL and chasing another red herring?

Under 1401 BIOS, any XMP profile must be enabled last after adjusting everything, otherwise it throws code 53, 79 etc upon reboot. If XMP is allowed to set all values to auto (value mismatch), instability still occurs, I may get missing 4 or 8 GB, Memtest might throw up some errors too. But manually entering all the correct XMP timings (making all values match) - everything works, no errors, passes quick tests etc. 1401 was closest to stable, but with 1502, am back to where I started despite using all exact same ratios, clocks and voltages, overclocked 40x only. Fails quick memtest and pi unless tested repeatedly or XMP disabled. Optimized defaults + XMP not useful too, am at a loss here. Not dissing the RVE board or updates, but just frustrated with serious bad luck with this entire combo. Will downgrade to 1401 and move on with life, but any advice is appreciated. If anyone else is using the exact Corsair kit, please let me know what works. Suggestions for other brands of kits would be welcome too.

Thanks guys.
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2 REPLIES 2

Praz
Level 13
Hello

One or more of the channels having different values is normal due to differences in jitter, crosstalk, impedance and so forth. The auto rules are good for the tertiary set of timings as well as RTL/IOL and IO settings.

thexchange
Level 7
Thanks for the quick reply, Praz. So I can now cross out that 'problem' from my checklist then, darn it. Only reason I've been trying to get the values to match is because I find the system boots well every single time with all values set, vs when I just leave them at auto. Looks like I'll have find another obscure thing to get my mind all worked up over with next, in the quest for the holy grail of STABILITY 😛 Either that, or just ditch XMP and OC and run everything the way the makers intended, lol.

On a sidenote, thanks to all these problems and wonderful folks sharing their experience here, I've definitely learnt a lot more each time. So thanks again, ya all!