Re: finding (or alternatives) 16GB 3866MHz DDR4 SDRAM UDIMMs?

On Tue, 2 Apr 2024 03:44:26 -0400, Paul wrote:

> On 4/1/2024 4:58 AM, David Chmelik wrote:
>> Can you still buy 4x16GB 3866MHz DDR4 SDRAM UDIMMs, such as two G.Skill
>> F4-3866C18D-32GTZR preferably without horrible 'RGB' LEDs (though if
>> only option and OpenRGB can turn off, we'd use this model)?  I searched
>> Google,
>> New Egg, Amazon, Best Buy, Ali Express, but closest are 3733MHz,
>> 4000MHz. We want to upgrade old PC--GigaByte GA-Z270-HD3P--with fastest
>> RAM, which GigaByte.com says is 3866MHz... can you even run 4000MHz at
>> all--stable at 3866MHz--or best switch down to 3733, 3666, or 3600MHz,
>> etc.?
>> 
>> Internet Relay Chat (IRC) gave unhelpful replies like 'use
>> DDR5'--GA-Z270-
>> HD3P can't--and someone saying that technology generation doesn't
>> 'scale' well with RAM (whatever that means) but we're not getting rid
>> of it nor using slower just because of vague/subject-changing IRC
>> statements.
>> 
>> Of course, if/when there are decent/better DDR5 SDRAM system-/logic-/
>> main-/mother-board options (see my 2024-1-4
>> alt.comp.hardware.pc-homebuilt thread asking about CPUs) I'll build a
>> new PC (for me, not replacing GA- Z270-HD3P (family PC) so saying 'use
>> DDR5' is irrelevant)... that is, if/ when a new DDR5 full/extended ATX
>> system-board has plain PCI slot(s) and preferably can run powerful AMD
>> Ryzen (7950X(3D) Zen4 or successor Zen5) or maybe Intel Core i9 almost
>> as powerful (threads) for computer programming/science (particularly
>> compiling large projects, which still, primarily needing larger number
>> of threads, only AMD is best at)... entirely unrelated to upgrading old
>> PC for the many years we plan to use.
>> 
>> 
> https://www.reddit.com/r/intel/comments/115th3p/
kabylake_i7_7700k_32gb_ram_support/
> 
>    https://benchmarks.pugetsystems.com/benchmarks/view.php?id=105243
> 
>        Intel Core i7-7700K CPU @ 4.20GHz Memory  64GB  (2x32GB)  3000MHz
>        Motherboard    MSI Z270 GAMING M3 (MS-7A62)
> 
> That says, basically, that there is no hardware barrier to using 2x32GB.
> I've had boards before, they simply do not have support for the highest
> density chips, even though the hardware is agreeable (enough address
> bits),
> and without support the timing settings are all wrong. For example, on
> my 4Core board from Asrock, the thing actually supported 2x2GB RAM, when
> even the VIA web page (the chipset maker!) reported it only supported
> 2x1GB.
> But without proper BIOS support, I would have needed to do 256 trials of
> memtest, to figure out the necessary settings. Not gonna happen...
> 
> On speed, I would stay at no more than 3600.
> Some people have experienced "BSOD-city" at anything over 2133,
> but that could be due to older generations of RAM chips.
> 3600 is much easier to find, and is "standard speed" for current gen.
> 
> What we don't know, is if the Gigabyte BIOS handles 32GB modules.
> 
> And I don't know if any computer shop support, will run 2x32GB DDR4-3600
> on XMP speculatively, and compare to 4x16GB double-sided DDR4-3600
> (which uses chips having half the density and might be more agreeable to
> the Gigabyte BIOS parsing). Any shops I've been in, their "RAM cabinet"
> is filled with garbage RAM. They never break open packs of boutique RAM
> and offer a testing service to identify a working module. You know,
> one shop, they'd never heard of memtest, so I fucking well had to give
> them a copy :-) Like, who should not be in the computer store business.
> Now we know. The shop that didn't know what memtest was.
> 
> It's the usual ugly situation, where the current generation DDR4 does
> not give a rats-ass about details, and older tech might indeed care
> about the details, as it's not quite as easy-going.
> 
> One other aspect, is automatic adjustments the BIOS makes, and Gigabyte
> is one of the more aggressive manufacturers (uses too much VCore when
> MSI uses less). There can also be bumping of PLL voltage when a higher
> speed RAM is inserted. The result is a 90C CPU, and difficulty avoiding
> throttling. If the CPU throttles, then all that "juicy" memory
> performance improvement, is tossed out the window like trash. These are
> things an owner can attempt to hand tweak (as Enthusiast boards expose
> the settings and bad choices can be overruled). The 7700K did not have
> very good TIM inside the thing (even though the curved lid makes it look
> like a soldered lid). It's hard to keep a CPU cool,
> if it's being tortured on voltage (90C versus 70C, if it were done
> properly).
> 
> It's a multi-variable problem. And in addition, some of the details we
> need, may not be on the RAM manufacturer web site. Even whether RAM is
> SS or DS is not necessarily on the master spec page. And since several
> densities of chips are available, and the RAM makers select which one to
> used based on daily spot price... it's just a trip to the "hardware
> casino". I can go to the computer store, buy two packs of RAM, one pack
> has sticks with 16 chips,
> the other pack has sticks with 8 chips (you can read out the details by
> dumping a CPUZ text report using the last pane in the interface).
> 
> I would try to borrow a 32GB stick, and "see what happens" :-)
> As a starting point. If it reports 32GB, woohoo!, 2x32GB here we come.
> 2x32GB, if it reports 64GB as expected (minus video card RAM decode
> perhaps), the signal integrity, and ability to hit 3600 when you flip on
> XMP, should be super-easy. I am a little more concerned about how easy
> the 4x16GB case will be, as some 16GB sticks will be DS, and if a 16GB
> stick is SS, it's using the same DRAM chips as a 32GB DS stick would be
> using. This means most likely, all the 16GB more or less, will be DS and
> using chips of half the density of the 32GB modules.
> If you needed to sell off 4x16GB, both 3200 and 3600 should still have
> some resale value, with the 3600 being easier to move. The box I'm
> typing on, uses 3200.
> 
> If flipping on XMP does not work, and your new config crashes,
> be warned that it takes *one week* of fiddling and testing,
> and the end result is most likely your 3200 or 3600 kit runs at 2400.
> That XMP setting saves a lot of work... when it passes memtest.
> 
> I'm not a RAM expert, because I don't know what all the settings in the
> BIOS do. As a hardware designer, I know what the "turn time"
> is, the time of flight to the module and back again. I know the
> theoretical concepts. But some of the labeling in the BIOS eludes me :-)
> RAM actually contains features that PC compatible computers do not use
> (some of the cycle abort features are not used).
> 
> As for CAS, some of the chipsets/generations have a lower limit on CAS.
> Normally, the modules can't quite make it that low, but there have been
> generations where indeed, you could buy a CAS3 and the BIOS would only
> go down to CAS4. And you'd be angry as a result.
> CAS is much higher now, and the minimum value is likely out of reach,
> so one less thing to worry about.
> 
> Summary: 2x32GB DS modules DDR4-3600 ? I'd gamble on that as the SI is
> better.
>          But if the BIOS stupidly reported only half the RAM ? Hmmm.
> 
>          4x16GB DS modules ? Getting XMP to work may be out of reach on
>          that generation, and then there's a week of fiddling to do and
>          whatever the intended speed, a lesser speed will result.
>          Current gen hardware laughs at the four DIMM case, the older
>          systems... less so.
>          Some people have run 4x8GB DDR4-3600 on the 7700K, but
>          generally they did not write up the details of the experience.
> 
>          Each case has different known-unknowns. [...]

Thanks!  So, if I still do this, I might try DDR4-3600MHz as seems highest 
widely-available, though in fewer cases DDR4-3733MHz is also.  However, 
I'm having second thoughts about overclocking RAM: some people 
knowledgeable about hardware said if you do, the system-board won't last 
as long and some capacitors go bad.  This is exactly what happened with my 
BioStar X470GTA this year: a capacitor popped off after almost three years 
usage, so likely I should've used fastest non-overclock RAM.  Also, though 
I had the GA-Z270-HD3P in an online shop cart and was going to checkout, I 
finally decided not to rather than maybe keep the GA-Z170XP-SLI it still 
has, and maybe don't overclock that either.  I've also found some our old 
PCs/servers could use RAM upgrades so may make another post asking about 
these (mostly/all not type of RAM in subject line).

I don't understand all the technical terms--just some of them--but the 
detail is pretty great.  I used to look at CAS & RAS speeds in the 1990s 
but maybe one doesn't matter anymore and they seem to have increased 
rather than decreased (which was happening for a while and which was 
better).