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Which DDR3 SODIMM to choose? (taking into account the speed and compatibility)


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Poll: Which DDR3 SODIMM to choose? (taking into account the speed and compatibility) (2 member(s) have cast votes)

Which option(s) would most probably give me the fastest machine (and a stable, reliable RAM)?

  1. adding a KINGSTON TECHNOLOGY DDR3 SODIMM Kingston 2GB 1333MHz CL9 - part no. KVR1333D3S8S9/2 (0 votes [0.00%])

    Percentage of vote: 0.00%

  2. adding a KINGSTON TECHNOLOGY 2GB 800MHZ DDR3 NON-ECC CL6 SODIMM - KVR800D3S8S6/2G (0 votes [0.00%])

    Percentage of vote: 0.00%

  3. removing the current module and putting in a new 2x2gb: CORSAIR DDR3 SODIMM Corsair 4GB (2x2GB) 1333MHz CL9 - CMSO4GX3M2A1333 (2 votes [100.00%] - View)

    Percentage of vote: 100.00%

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#1 domino loto

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Posted 23 January 2013 - 07:57 AM

Hello,

I'd like to choose a RAM for an upgrade of Motion Computing J3500 tablet PC. Please consult me a little about the speed and compatibility.

I need SODIMM DDR3 memory for this tablet PC (there is 2gb in it now; I need to have 2x2gb). PC specification says that "DDR3 memory operating at 800MHz". CPU is Intel i5 1.33GHz.

It's important for me that all the RAM which will be in the PC after upgrade would work as fast as possible (I mean the access speed (ns)).

There is one RAM module of 2gb PC3-10600 in this model, and I want to upgrade it to 4gb total RAM (2x2 gb). However I see that J3500 spec. says that the memory should run at 800MHz, and there are little options of exactly this speed memory here where I live at the moment. Some salesman has suggested me to put an additional 1333MHz RAM module in it. I know that in such a case RAM modules would clock down to 800MHz in this PC. By the way, at the same time their CAS latency (CL) values would also change. But it is exactly the reason why I don't know what real RAM speed would be after these MHz and CL changes.

I'm considering 3 options now:
1) adding a KINGSTON TECHNOLOGY DDR3 SODIMM Kingston 2GB 1333MHz CL9 - part no. KVR1333D3S8S9/2
2) adding a KINGSTON TECHNOLOGY 2GB 800MHZ DDR3 NON-ECC CL6 SODIMM - KVR800D3S8S6/2G
3) removing the current module and putting in a new 2x2gb: CORSAIR DDR3 SODIMM Corsair 4GB (2x2GB) 1333MHz CL9 - CMSO4GX3M2A1333 (would in this case RAM work in dual channel mode?)

Which option(s) would most probably give me the fastest machine (and a stable, reliable RAM)?

As I mentioned, the most important thing for me is to have the PC (or more exactly, the RAM in it) to be running fastest (I mean the access speed (ns)).
And, well, having a stable, reliable RAM is important too, naturally.
The price is not important.

P.S. What info I have found so far:
  • access speed: http://en.wikipedia.org/wiki/CAS_latency#Effect_on_memory_access_speed
  • SPD chip has a table of frequencies and CLs programmed inside, e.g.: http://www.tomshardware.co.uk/forum/284316-12-latency-ddr3-1333-operating-533mhz
  • Dual Channel should make the RAM run a little faster, am I correct?
  • Some hardware person has told me that if PC/mobo is "designed to run at 800MHz", then it's best to put exactly 800MHz RAM in it, otherwise it's not good for the electronics of the whole PC. What do you think of it?
  • Another person told me this: "RAM speed is only relevant in mobos with FSB. Intel i-series is not using FSB, but QPI bus instead, therefore RAM frequency has no effect, and CL has no effect. Usually 1333MHz is CL9 (or even 1600MHz - also CL9), and there won't be any faster." This guy suggests me to use option (3), just to have exactly same RAM modules for the stability.

Edited by domino loto, 23 January 2013 - 10:32 PM.


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#2 domino loto

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Posted 23 January 2013 - 10:47 AM

Actually looks like the CPU of this PC is using DMI, not QPI:

  • Although some Core i7 processors use QPI, other Nehalem desktop and mobile processors (e.g. Core i3, Core i5, and other Core i7 processors) do not—at least in any externally accessible fashion. These processors cannot participate in a multiprocessor system. Instead, they directly implement the DMI and PCI-e interfaces, obviating the need for a "northside" device or a processor bus of any type. - from wikipedia
  • http://en.wikipedia.org/wiki/List_of_Intel_Core_i5_microprocessors says: "FSB has been replaced with DMI". (And only i7 CPUs say "FSB has been replaced with QPI".)
Does using DMI interface make RAM frequency and CL irrelevant to the actual access speed of RAM?

Edited by domino loto, 23 January 2013 - 10:31 PM.


#3 hamluis

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Posted 02 February 2013 - 07:30 PM

http://www.crucial.com/upgrade/Motion+Computing-memory/(OTHERS)/J3500+Tablet+PC-upgrades.html

You seem to be assuming...that minor changes in RAM specs...make a great deal of difference in a system. They don't. The amount of RAM instaled/useable is the key factor to consider, IMO.

Louis

#4 domino loto

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Posted 03 February 2013 - 12:41 PM

The amount of RAM instaled/useable is the key factor to consider, IMO.


The amount of installed RAM is maximum and equal in all three cases, it's 4 GB. My question was about the speed (throughput) and compatibility..

#5 hamluis

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Posted 03 February 2013 - 06:46 PM

Compatibility...depends on the motherboard manufacturer.

Some boards are picky about what RAM modules are inserted...others are not. That's one reason why motherboard manufacturers publish a Qualified Vendor List for RAM modules which are known to perform in an optimal/acceptable manner. Find the specs for your board, take a look...if you like.

The documentation for the system may also reflect this info.

The speed/throughput of any RAM module...will be determined by the motherboard specs for RAM and the clocking set/controlled by the motherboard.

I suggest you await inputs from someone who knows a lot more about these things...than I do :). Many members here fall into that category.

Louis




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