Which memory stick is "faster", and are the two "compatible"?

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  1. Posts : 2,752
    Windows 7 Pro x64 (1), Win7 Pro X64 (2)
    Thread Starter
       #11

    Layback Bear said:
    I have no idea what is in a Lenovo motherboard manual. Have no reason to know.
    My systems have motherboard manuals.
    This isn't a motherboard that I bought... it's a laptop.

    Sure, the various motherboards I've bought myself over the years for the several home-built machines I've constructed came with a very detailed manual. And in particular, the documentation regarding memory is typically quite extensive. but motherboard documentation is a different kettle of fish, intended for a system builder and it needs to provide very explicit details about lots of things. In contrast, a laptop user guide is generally intended for a different category of user.

    I agree with you insofar as motherboard documentation. But we're not discussing a motherboard here.


    If the manual tell you nothing does the motherboard have 2 colored ram slots.
    If so most likely two of the same color will be the proper slots to use for two sticks of ram.

    Just try two of the same color and see what happens. It won't hurt anything.
    If those two colored slots don't work try the other color.

    If that don't work just fill all slots. That has got to work if all the ram module and motherboard slots are working properly.
    You're talking about a motherboard here. This isn't how a laptop interior looks.


    What I find here you only have two ram slotsand two m.2 slots.

    Page 74 & 78
    http://www.ok1.de/thinkpad/HMM/p70_h...sp40j65113.pdf

    Am I looking at the same computer?
    Yes, that's the hardware maintenance manual for the P70. But you're misinterpreting what you've pointed to. There are two RAM "bays", not two RAM "slots". And each "bay" has two "slots", thus producing a total of four memory "slots".

    Page 74 describes one of the two memory bays, in particular this is the one on the underside of the machine accessed simply by removing the bottom cover. This bay has TWO SLOTS... which I've empirically discovered to be #2 and #4.

    Page 78 describes the second of the two memory bays, in particular this is the one under the keyboard which must be removed (with three screws) in order to access it. This bay also has TWO SLOTS... which I've empirically discovered to be #1 and #3.

    So, two memory bays, each of which has two SODIMM sockets. Total of four memory sockets available.

    The M.2 bay is completely separate, and is described starting on page 72. This bay has two PCIe sockets, supporting either one or two PCIe M.2 SSD/NVMe devices (configured either individually or as RAID). This thread is not concerned with the M.2 bay.


    Anyway, once I get the second Crucial memory card I will do the requisite "corrective surgery" as I've previously described. Once I've got these identical matching two cards in "paired sockets" #1 and #3 (under the keyboard) I'm sure I will get "dual".
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  2. Posts : 13,576
    Windows 10 Pro x64
       #12

    Yep, laptops are a different breed, but if 2 and 4 are on the bottom I would think that would put you in dual channel mode, but you have the manual, so you know best.
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  3. Posts : 2,752
    Windows 7 Pro x64 (1), Win7 Pro X64 (2)
    Thread Starter
       #13

    AddRAM said:
    Personally, I would've gotten another Samsung stick, but the difference in numbers is nothing to worry about.
    In retrospect we would never make mistakes.

    Lenovo has priced hardware upgrades for this new thinkpad P50/P70 product line very strangely. They wanted $120 for their additional 8GB, instead of the $45 Crucial asks. That's the only reason why I opted not to get all 16GB from Lenovo, as I assumed the Crucial memory would be identical.

    Since I've never purchased Crucial memory to upgrade other Lenovo machines (e.g. M93p desktop) that didn't EXACTLY match the Lenovo-provided Samsung memory timings in those machines, I had no reason to suspect anything different in this case of the P70. I suspect Crucial would also be surprised to see that their memory isn't an exact match for the Samsung memory.

    Anyway, once both 8GB memory cards are from Crucial and identical and installed in slots #1 and #3, this case will be closed.
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  4. Posts : 2,752
    Windows 7 Pro x64 (1), Win7 Pro X64 (2)
    Thread Starter
       #14

    AddRAM said:
    Yep, laptops are a different breed, but if 2 and 4 are on the bottom I would think that would put you in dual channel mode, but you have the manual, so you know best.
    Once again, the two 8GB memory cards as currently installed are NOT in #2 and #4. Nor are they in #1 and #3. They are in #3 (Samsung) and #4 (Crucial), only because I didn't know there was any special consideration here as the documentation (such as it is) mentioned nothing.

    So to avoid bothering with the removal of the keyboard I simply installed the one 8GB of Crucial memory that I'd ordered in the easiest memory bay to access, on the underside of the laptop. I arbitrarily put in one of the two slots there, which turned out to be #4. Since both of these slots were free and available, it was clear to me that the one 8GB of Samsung memory had to be in one of the other two slots under the keyboard, which turned out to be #3. But at the time I didn't realize there might be a consequence of doing what I was doing. Of course had I known there would be a negative consequence (i.e. "single") I would not have done it that way.

    I can probably use #2 and #4 (underside of laptop) and get "dual" mode, same as I can use #1 and #3 (under the keyboard). But at the moment the Samsung 8GB is under the keyboard in #3. So regardless of how I fix this, I'm going to have to remove the keyboard to get to that bay which currently holds the 8GB Samsung memory in #3.
      My Computer


  5. Posts : 13,576
    Windows 10 Pro x64
       #15

    And when you do remove the keyboard, consider putting both of the new crucial sticks there, that way, if you ever actually decide to add more, you won`t have to remove the keyboard again. But I seriously doubt you`ll ever need more then 16 GB with a laptop.

    Just an FYI :)

    I understood you have 1 stick under the keyboard and 1 on the bottom. Wherever you put the new Crucials, you`ll be removing the keyboard, it should be no problem :)
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  6. Posts : 2,752
    Windows 7 Pro x64 (1), Win7 Pro X64 (2)
    Thread Starter
       #16

    More insight into the specific details of the Samsung vs. Crucial memory, this time from HWINFO:



    So if I'm reading this correctly, it looks like these ARE essentially identical (certainly at the 1066Mhz that it's running at), except at the lowest frequencies. And even at the lowest frequencies it appears that the Crucial memory is faster, not slower, than the Samsung memory.

    Am I not reading this correctly? I wonder why CPUZ reports these numbers very differently for the Crucial memory?


    To back up the above charts, here are the memory details from HWINFO.





    Again, does this not appear to back up the characterization that the Crucial memory is the same as, if not better than, the Samsung memory?

    So it's even more evident to me that it was the unfortunate choice of the un-paired SODIMM sockets which has caused the memory to operate as "single", not any slight mismatch in memory timings (which now don't appear to be different at all). In fact they do appear to be a match at 1066Mhz.

    And if that's true, then tomorrow I will perform surgery on the laptop and move the currently installed Crucial memory from where it is now on the underside of the laptop into the second slot of the other memory bay under the keyboard. My theory is that this is all it should take to get "dual" mode behavior.

    If the operation is a success, I will simply return the second 8GB of Crucial memory that I bought last night, since it's not necessary. In fact I now believe the Crucial memory to actually be a "match", so that re-locating it to the proper SODIMM socket will give me "dual" mode operation.

    More news tomorrow.
      My Computer


  7. Posts : 2,752
    Windows 7 Pro x64 (1), Win7 Pro X64 (2)
    Thread Starter
       #17

    Ok. The operation was a success. The patient will play the violin again.

    Getting to that second memory bay under the keyboard was certainly not an easy surgery, but I have emerged victorious. I removed the Crucial memory from where I had mistakenly installed it originally in the easy-to-access bay on the underside of the laptop, in what was slot #4. I then reinstalled it in the available second slot which was in fact #1 in the under-the-keyboard bay, along with the Samsung memory already installed by Lenovo in slot #3.

    And as is shown by HWINFO, the Samsung and Crucial memory cards are truly identical. And now that they are installed in "paired slots (#1 and #3)" the memory is now behaving in dual-mode.




    I don't know why CPUZ shows things the way it does when looking at the two cards shown in the SPD tab, but CPUZ also confirms that the memory is behaving in dual-mode.




    So as it turns out, the Crucial memory is 100% perfectly compatible with the P70 and the Samsung memory. Also, at 1066Mhz both memory cards operate at the identical speed.

    I will return the second Crucial memory card I ordered in panic, when I thought "single mode" was because the two cards were not identical and I intended to replace the Samsung card with the second Crucial card in order to have a matched set. Turns out this was untrue, and unnecessary. It was actually that I'd installed the Crucial card in an unpaired slot which was responsible for "single mode".

    Case closed.


    NOTE: Had I purchased 2x8GB=16GB of memory on the P70 from Lenovo, I'm sure they would have installed both cards in this under-the-keyboard bay. That would have then left the easy-to-access two-slot second memory bay on the underside of the laptop for further expansion (of another two matched cards). It was only that I decided to go with the standard 8GB and save money ($45 vs. $120) by buying my own second 8GB, that I ended up having to go through this keyboard-removal surgery myself, in order to properly utilize the paired-slot #1 (which unfortunately was under the keyboard) in order to accomplish "dual-mode".

    Case closed.
      My Computer


 
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