RAM Speed limit for XPS 15 9560 (Kaby lake)

Discussion in 'Dell XPS and Studio XPS' started by andy_xps, Apr 25, 2017.

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  1. andy_xps

    andy_xps Newbie

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    Hello,

    I just purchased a XPS 15 9650 model with in-built 16GB RAM. I need to max out to 32GB RAM
    but, I've already came across different speeds like DDR4-2400, DDR4-2666 in a few manufacturers.

    Could someone please help by advising the maximum RAM speed to go for XPS 15 9650
    (where the entire speed is actually used by XPS 15) ?

    I assume XPS 15 9650 has a certain limitation from which the excess speed becomes unused.
    So, probably getting an extreme high speed is not worthwhile.

    Kindly advise and Thank you,
     
    Last edited: Apr 26, 2017
  2. Althernai

    Althernai Notebook Virtuoso

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    According to Intel, the 7700HQ supports DDR4-2400, LPDDR3-2133 and DDR3L-1600. I just checked the memory speed on my 9560 and it is DDR4-2400. Then again, Dell does offer the Precision 7520 with a 7700HQ and a DDR4-2667 option so it might be compatible.

    When you say you found DDR4-2666, do you mean that you've seen an XPS 15 with that RAM or that you found RAM of that type in a store?
     
  3. andy_xps

    andy_xps Newbie

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    I had seen those RAM types in stores (online) not on actual XPS 15 machine. For example on Crucial, they offer these:
    Ballistix Sport LT 32GB Kit (2 x 16GB) DDR4-2400 SODIMM
    Ballistix Sport LT 32GB Kit (2 x 16GB) DDR4-2666 SODIMM

    Both of these are listed under the compatible sections for XPS 15 9650, but does this extra speed (2666) make an affect,
    or would the hardware only pick speeds up to 2400 and the rest goes unused - this is what I'm trying to understand.

    Although officially Dell says it takes DD4 - 2400MHz, some RAM models claim to offer compatibly for higher RAM speeds, which isn't officially a Dell's acknowledgement.

    I do Analytics work with big datasets and I would want the best RAM speeds possible, just need to make sure XPS 15 actually uses it and not wasted.


     
  4. GoNz0

    GoNz0 Notebook Virtuoso

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    You can buy 2667 or 2666 as some kits come as (both the same), they may drop back to 2400 speeds but this can also be beneficial over a stock 2400 kit as the 2400 latency will usually be lower.
    Considering the 7520 isn't built on the same chassis as the 9560 you may just get 2400 speeds.
     
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  5. _sem_

    _sem_ Notebook Deity

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    At Userbenchmark there are a few RAM high scores by G.SKILL 2666, it appears they run at 2666. Every 2666 may not.
     
  6. pressing

    pressing Notebook Deity

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    When I was shopping for RAM, HyperX 2400 had the lowest CAS latency.

    Low CAS latency might make your laptop a slight bit faster but good luck noticing any difference. Plus, there are so many bottlenecks in a small laptop and RAM is so expensive these days, I would be wary of paying extra money for low CAS latency RAM.

    Fast, large nvme options may be a better place to invest in performance depending on your usage...

    Edit - as a general matter as speed increases, unfortunately, so does CAS latency. So the "improvement" from 2400 to 2667 may be vanishingly small.
     
    Last edited: Apr 26, 2017
  7. DackEW

    DackEW Notebook Consultant

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    The truth is out there, so Buy, buy, buy, that is the only way to find out the truth. Newegg also have DDR4 3000MHz Sodimm!!!, so go ahead and report back, please!
     
  8. Mr.Bricss

    Mr.Bricss Notebook Enthusiast

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    Kaby Lake should easily eat 2800MHz of RAM.

    FYI:
    Skylake - max RAM frequency is 2666 MHz
    Kaby Lake - max RAM frequency is 2800 MHz


    I have upgraded my 9550 model with Corsair Vengeance 2666MHz RAM and it's works like a charm. Showing 2667MHz speed in BIOS and OS.
     
  9. GoNz0

    GoNz0 Notebook Virtuoso

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    Good to know.

    Sent from my SM-G920F using Tapatalk
     
  10. pressing

    pressing Notebook Deity

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    How are you getting
    Edit - As noted below there are some 6700HQ 9550 and Precision units running above 2133MHz. I don't think the i5 can...
     
    Last edited: Apr 28, 2017
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