Post by David ChmelikCan 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.
Paul