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Date:      Thu, 11 Jan 2018 21:05:03 +0300
From:      Mehmet Erol Sanliturk <m.e.sanliturk@gmail.com>
To:        Aryeh Friedman <aryeh.friedman@gmail.com>
Cc:        galtsev@kicp.uchicago.edu,  Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>,  FreeBSD Mailing List <freebsd-questions@freebsd.org>
Subject:   Re: OT: Max system physical memory
Message-ID:  <CAOgwaMsH14bPAsDyTpwnNU1hULTkMZ6FuAaswr=aJNxTo=obxA@mail.gmail.com>
In-Reply-To: <CAGBxaXkGNoOzsTqUF3n5HipweBg4NUib__OKCXuPPZmq7-OAJA@mail.gmail.com>
References:  <CAGBxaX=+YUuDBOp5n1Kjq6xaJmjEpZ8kWARNMnE_3LwBkNM6GA@mail.gmail.com> <44wp0ofr1w.fsf@be-well.ilk.org> <50615.108.68.170.208.1515682927.squirrel@cosmo.uchicago.edu> <CAGBxaXkGNoOzsTqUF3n5HipweBg4NUib__OKCXuPPZmq7-OAJA@mail.gmail.com>

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On Thu, Jan 11, 2018 at 6:08 PM, Aryeh Friedman <aryeh.friedman@gmail.com>
wrote:

> On Thu, Jan 11, 2018 at 10:02 AM, Valeri Galtsev <
> galtsev@kicp.uchicago.edu>
> wrote:
>
> >
> > On Thu, January 11, 2018 7:44 am, Lowell Gilbert wrote:
> > > Aryeh Friedman <aryeh.friedman@gmail.com> writes:
> > >
> > >> My computer (HP Pavilion P7-1234, FreeBSD 11.1-RELEASE [amd64]) has 2
> > >> 240
> > >> pin DIMM (DDR3, PC3-10600) the manual says the max memory is 8 GB but
> I
> > >> see
> > >> some 16 GB packages (2x8GB).   If I put one or two of these in will it
> > >> see
> > >> the extra memory?
> > >
> > > Probably not.
> > >
> >
> > It is hit and miss. It is possible that specifications were written based
> > on largest available modules at the moment of writing. If replacement
> > modules are compatible with memory controller (i.e., say, the same
> > PC3-10600), it is possible they will work. There still is the chance they
> > will not work reliably, _IF_ there are some less trivial specs of memory
> > controller are involved. Such may be: bus amplifiers may only handle up
> to
> > this capacitive load before signals go out of specs. In general, larger
> > RAM has larger numbers of address inputs connected to given lead, which
> > may entail larger capacitive load. System board layout may have its
> impact
> > here as well. Apart from that (and maybe some internal schematic
> specifics
> > of memory controller), there is nothing fundamental about 8 GB RAM limit,
> > so it may work. But chance is it will not.
> >
> >
> sysutils/dmidecode disagrees with the manual thus deeping my confusion (I
> bought the memory and use it in an other machine that does support upto
> 32GB and only has 8 spread across 2 VM's):
>
> oot@lilith:~ # dmidecode -t memory
> # dmidecode 3.1
> Scanning /dev/mem for entry point.
> SMBIOS 2.7 present.
>
> Handle 0x000A, DMI type 16, 23 bytes
> Physical Memory Array
>     Location: System Board Or Motherboard
>     Use: System Memory
>     Error Correction Type: None
>     Maximum Capacity: 128 GB
>     Error Information Handle: Not Provided
>     Number Of Devices: 2
>
> Handle 0x000C, DMI type 17, 34 bytes
> Memory Device
>     Array Handle: 0x000A
>     Error Information Handle: Not Provided
>     Total Width: 64 bits
>     Data Width: 64 bits
>     Size: 4096 MB
>     Form Factor: DIMM
>     Set: None
>     Locator: A1_DIMM0
>     Bank Locator: A1_BANK0
>     Type: DDR3
>     Type Detail: Synchronous
>     Speed: 1333 MT/s
>     Manufacturer: Samsung
>     Serial Number: 938D8E07
>     Asset Tag: A1_AssetTagNum0
>     Part Number: M378B5273CH0-CH9
>     Rank: 2
>     Configured Clock Speed: 667 MT/s
>
> Handle 0x000E, DMI type 17, 34 bytes
> Memory Device
>     Array Handle: 0x000A
>     Error Information Handle: Not Provided
>     Total Width: 64 bits
>     Data Width: 64 bits
>     Size: 4096 MB
>     Form Factor: DIMM
>     Set: None
>     Locator: A1_DIMM1
>     Bank Locator: A1_BANK1
>     Type: DDR3
>     Type Detail: Synchronous
>     Speed: 1333 MT/s
>     Manufacturer: Samsung
>     Serial Number: 938D8C71
>     Asset Tag: A1_AssetTagNum1
>     Part Number: M378B5273CH0-CH9
>     Rank: 2
>     Configured Clock Speed: 667 MT/s
>
>
>
> --
> Aryeh M. Friedman, Lead Developer, http://www.PetiteCloud.org
> _______________________________________________
>
>


Another problem may be required energy to feed higher capacity memory chips
. If the currently available  slots are not able to support the required
energy , over time they may cause hardware failure and/or memory access
errors .


Mehmet Erol Sanliturk



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