XMP I vs. XMP II

[SteverinoLA]

I've searched and search both Google and forum for a definitive answer to this but no go. What is the difference b/t Asus XMP I and XMP II? This is not XMP 2.0 spec I'm referring to but the option BIOS when enabling XMP profile. You can select XMP I or XMP II, but what is the exact difference? Probably one is the default XMP 2.0 JDEC values and the other is enhanced by Asus? If true, which one is which and are the Asus enhancements for performance ( tighter timings) or reliability (looser timings)?

[SteverinoLA]

Silent Scone@ASUS wrote:
Hello,

The DIMM profile may offer either better or worse compatibility depending on the memory kit and CPU IMC. That is why they're both available, and you're free to choose.

That's the answer, thanks. Like most people on this forum, I'm a dork that sleeps better at night knowing that every aspect of my box is tweaked to run as fast as possible. I'm rock solid at either I or II.

So I'll take the liberty of pretending you also said this: If it really matters to you, you can spend days benchmarking both I and II, and you can go even further tweaking the individual RAM settings to get even closer to the edge. But if all you're doing in just playing games and web browsing, you won't be able to tell any difference bt I or II. Just use XMP I since we validated these settings for stability.

[Crasje]

Very interesting, so if your RAM is on the memory list from your MOBO , you use profile 1, if not, profile 2

I tried to update my 2 x 16GB (CMT32GX5M2X5600C36) to 4 x 16GB but ran into a lot of issues. Could not run my memory at 5600Mhz. This memory is in the list so I must run XMP 1.

Now I ordered 2 x 32GB (CMT64GX5M2B6000C40), which is 6000Mhz and this is NOT in the list, so for this memory I must run XMP II.

What I found strange is that when you buy this memory, and you plug it in and set it too auto. I didnt run at 5600Mzh but 4000. Perhaps I am bit old school but if you pay money to have the Ram with this frequency, you would expect it to run at that. 

Never to old to learn.

*note to myself. Before adding the new memory, set Memory in the bios to auto first. Add the memory, check frequency and then change to XMP II.

[Murph_9000]

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@Crasje wrote:

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What I found strange is that when you buy this memory, and you plug it in and set it too auto. I didnt run at 5600Mzh but 4000. Perhaps I am bit old school but if you pay money to have the Ram with this frequency, you would expect it to run at that. 

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Defaults / auto give you the standard, not-overclocked speed.  The DRAM chips on your DIMMs are not 5600 MT/s chips, that is an overclocked speed.  All XMP/DOCP/EXPO speeds are non-default overclocked speeds.  Gamer/enthusiast memory is generally marketed and sold as an overclocked speed, and the memory vendors often don't make that obvious.  They take DRAM chips which have been manufactured as, for example, DDR5-4800, then filter them into bins based on testing how the individual chips perform above their standard speed.  They then construct DIMMs from the binned chips, test them, and set what they believe is the fastest overclock speed and timings they can get away with as the XMP/DOCP/EXPO profile.

E.g. my Crucial DDR4-3600 DIMMs are actually Micron DDR4-2666.  Micron manufactured the silicon and package it into DRAM chips rated at 2666 MT/s.  The resulting DIMMs have a JEDEC SPD speed profile of 2666 CL20, but a XMP overclock profile of 3600 CL16.  In that particular case, Crucial have a slight advantage by being a division within Micron, rather than a separate company.

The board vendors need to make the defaults/auto speed the non-overclocked speed, aka the JEDEC speed, to try to minimise cases where people can't get into BIOS setup.  It makes sure that you should be able to clear CMOS and get back into the BIOS after a failed overclocking attempt.