CMK32GX5M2B6400C32 - SK Hynix A die or M Die?

[Jay85]

People who have bought this RAM, which did you get? A Die or M Die?

Looking at tinkering with a set and there's mixed reviews on what they actually got shipped.

Corsair Vengeance LPX 32GB (2x16GB) DDR5 PC5-51200C32 6400MHz Dual Channel Kit

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[JollyJamma]

It's probably a mixture of both if you're not sure what they use. It shouldn't make a huge difference either way, as long as it's Hynix it should be good enough.

I would probably just go watch a Buidzoid RAM buying guide and then buy whatever he says is probably A or M die. He knows how to tell from speed and timings.

 

[Jay85]

Thanks! Its for my 12700k build, got my ram today and can confirm its SK Hynix, pretty sure its A die too. So far stable at 6800mhz on xmp tweaked timings. Gonna push it until no boot then revert back to last best settings and tweak the timings. This stuff is awesome so far! My Samsung b die hit 6200 max with tweaked timings.

 

[Jay85]

Ended up with 6800mhz with timings 34-39-39-86 2T. I can post at 7000mhz with the same timings but it won't pass any test, just blue screens.

I tried with unlocking the voltage for VDD and VDDQ to set 1.45v but it won't even post at that voltage for some reason. I also tried 34-39-39-76 6800mhz but my results were slightly worse on the read write so sticking with 34-39-39-86 2T unless someone tells me to try anything else otherwise.

SA and Cache voltage set to 1.3v, IMC voltage left on auto.


It's possible that loosening my P Core overclock and dropping the voltage on that might help with stability too. My E cores are turned off because of Star Citizen.

Edit: This is with a 12700k with a crappier memory controller, i could probably go quite abit higher with a 14600k... contemplating it.

 

[Jay85]

 

[JollyJamma]

Try get your tertiary timings down a bit - you’ll notice a difference.

That being said, it does sound like you’re fighting either a weird BIOS or a bad mem controller.

 

[ATIorNvidia]

12th gens have notoriously bad memory controllers

 

[Jay85]

Try get your tertiary timings down a bit - you’ll notice a difference.

That being said, it does sound like you’re fighting either a weird BIOS or a bad mem controller.

I tried again today, it just won't take. Either blue screens or random black screens so its not stable enough. Throwing more voltage at it seems to do little as well even though SK Hynix should be good for 1.5v, though i've kept it at the limit 1.435v so i don't have to enable high voltage.

I'm putting it down to the IMC on the 12700k,this really makes me want to get a 14600k to mess around with because i know i can get this to go higher. It will even post at 7000mhz but not stable if i start using applications.

12th gens have notoriously bad memory controllers

This is my thought too.

 

[Jay85]

So after about an hour on Star Citizen, game froze and CTD. From experience, SC is really good at weeding out bad memory overclocks so i took this as a sign that my Overclock wasn't stable enough.

Went back into the bios to tweak some more, without delving into the much more complex voltages with VPP etc i couldn't get 6800mhz stable. Infact the more i tweaked the worse it got where it would CTD shortly after joining the game.

I then remembered that an overclock on the core might also contribute to unstable memory performance so back i went to tweak the core voltages and core clock. Ended up downgrading from 5.2ghz to 5.1ghz all core at just over 1.3v (i think i can go lower but got too tired). I might try and set individual cores to 5.2 and leave the rest at 5.1 and see how that goes.

With this set however i was able to set 6600mhz with tighter timings and ended up with 32-38-38-74. Still tweaking this as i think i can bring the tertiary timings even lower now that my Vcore isn't as high and there's less voltage going through it. This is at the default XMP Tweaked settings at 1.4v.

Also note, this is with the IMC voltage at auto which reads 1.31v by default. I've heard that upping this can help but not sure what i should really be upping it to, so if anyone has any suggestions for IMC Voltage, VPP etc please drop a line .

 

[Jay85]

So it turns out i have SK Hynix M die after confirming with the good people over at the Buildzoid discord channel. They also pointed out that my serial number is something new that corsair has started doing which doesn't show the date of manufacturing. The dimms are also numbered -1 and -2 for anyone wanting to know what that means.

With the m die kit i was able to use Buildzoids guide and use his timings on this kit and so far i've ended up with this at 6600mhz.

Voltages:
SA 1.15
CPU input 1.9v
VDD 1.42v
VDDQ 1.42v
IVR Transmitter voltage 1.4v

I have a mild overclock on my p cores on my 12700k @5.1ghz all core with e cores turned off and an offset voltage with a negative setting (no voltage adjustments for vcore).

Also very happy with the latency at 57.5ns, i believe this is actually higher than it should be as my system is quite clogged with a lot of background applications running. I reckon if i did this in safe mode the result would be a lot more consistent and should be lower.





just did a 1 hour run on OCCT without any errors so im calling it stable. Will test in SC and see how that goes as Star Citizen is usually very memory sensitive.

Tomorrow i intend on bringing my primary timings down abit more before i fiddle with my tertiary timings. Gonna go for a 32-38-38-28 if i can and see how i get on.


Learnt so much in the past week on memory overclocking its honestly awesome, still very complicated but having this knowledge is pretty powerful in gaining performance here and there.

 

[Jay85]

My last post in this thread incase anyone comes up against the same thing.

The model number on my kit is abit weird even though its an M die, its PMIC is locked to 1.435v denoted by the "B" in the model version.




If you want an SK Hynix kit thats overclockable past the pmic's limitation at 1.43v then you'll want to get a kit that has a "X" in its model number for instance (CMK32GX5M2X6200C32) is a SK Hynix A or B die kit that allows PMIC unlock.

Source

I've figured that unlocking is great but you'll run into another issue of temperature especially on the vengeance kits where the heatspreader isn't particularly great so a pad change would help or a fan placement over the RAM. I'm able to run my kit upto 60c without errors but i know some people have had issues in the 60c region.


With that in mind for my particular M die kit, i am only able to run 32-39-39-28 with a few sub timing tweaks stable at 6600mhz. Voltage lock means i can't go any further and i'm at my limit.