64GB RAM - 2x32, or 4x16?

Discussion in 'Hardware Components and Aftermarket Upgrades' started by jack574, Dec 10, 2019.

  1. jack574

    jack574 Notebook Consultant

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    Hi. Which of these RAM configurations would be better for a Dell Precision 7740 laptop with i7-9850H processor?

    I'm not bothered about keeping slots free for upgrading - just looking for best performance now.

    Thanks
     
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  2. Chastity

    Chastity Company Representative

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    Depends on your workload. In theory, having all 4 populated will give you the best performance, as it maximizes parallel throughput. Also, using 2 row RAM vs 1 row also increases throughput. 16GB modules should be dual row, as are 32GB ones.
     
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  3. jotm

    jotm Notebook Evangelist

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    ARK says that processor supports 128GB, so without a doubt 2x32GB - you can upgrade later cheaper and faster.

    2 modules will use less power and generate less heat than 4.

    Performance difference is unnoticeable, you only have 2 channels.

    Resale value of 32GB sticks is higher.

    From experience, upgrading 4x4GB to 4x8GB sticks was a pain, had to replace all modules, and sell the old ones. Always good to have just empty slots - decide you want more RAM? Pop in a new module or two.
     
    Last edited: Dec 11, 2019
  4. hmscott

    hmscott Notebook Nobel Laureate

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    A new 3700x build had 2x8GB to start, and was running great - VM was system managed set to 16GB on 2TB boot SSD (Corsair MP600), and I thought I had enough memory...

    Then it was time to start building VM's so I found: Corsair CMK64GX4M2E3200C16 Vengeance LPX 64GB (2 X32GB) 16-20-20-38 DDR4 3200 on sale for $290 @ Central Computers
    https://www.centralcomputer.com/cor...2gb-ddr4-3200-1-35v-desktop-memory-black.html

    And it's running great, with the 64GB to work with the system running my normal daily setup is showing I am using 15GB++ before I start loading VM's.

    I've got 2 slots left, and I wouldn't be surprised to see a need for another pair of 2x32GB's in my future when I start loading up VM's... I hope CC keeps the price low.
    It looks like you have 4 slots and plenty of configuration options, how those slots are spread out can make expansion a pain from the stock configuration if you are doing it on your own, if you can configure it on order with a full boat (all 4 slots filled) that would be best.

    If you get 2 slots filled by Dell (or reseller), then later you have to find the same memory make / model / batch to be sure it's compatible. Always get pair or quad packs of matched memory rather than try to get disparate batches of memory to work together. It might work, but it might not.

    Price is a factor too, the prices are low now and buying all 4 is cheapest in a long time. Kinda trying to talk myself into picking up another pair while CC has them in stock so I can swap for another pair if the 1st 2nd pair I get isn't compatible.

    So if you can swing it get 4x 32GB now... :)

    Memory Table 1. Memory specifications
    https://www.dell.com/support/manual...a070cc-7772-48fd-bddc-84b148afe28e&lang=en-us
     
    Last edited: Dec 11, 2019
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  5. ssj92

    ssj92 Neutron Star

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    I recommend 2x32GB if price isn't an issue.

    You can always upgrade in the future if needed by adding another 2x32GB.

    4x16GB will mean you need to buy 4x32GB in the future.
     
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  6. jack574

    jack574 Notebook Consultant

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    Thanks guys. The difference in price between 2x32 and 4x16 is negligible (one is £695 and one is £672).

    I appreciate the upgrade issue (i.e. 2x32 is better in that respect, and the point about having to match modules in the future etc), but I'm purely after advice on the performance differences between the two configurations. The upgrading issue I can decide on myself. Doubt I really need 64GB anyway, so pretty sure I'll never need 128.

    Reading the answers above, it seems that in theory 4x16 is better, but in reality it's negligible?

    Thanks!
     
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  7. ssj92

    ssj92 Neutron Star

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    You won't see any noticeable difference in performance between 4x16GB and 2x32GB.

    Here's where the importance comes in....speed and latency.

    Higher speed and lower latency will be better. So if we are looking at like 4x16GB 3200Mhz vs 2x32GB 2666Mhz etc then I'd choose the faster 3200Mhz.
     
  8. hmscott

    hmscott Notebook Nobel Laureate

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    It varies by motherboard implementation. You'd need someone that owns that make / model / configuration to actually try it to see if there is a difference in performance. And, your specific application needs will make a big difference in whether you'll notice differences in configurations.

    Generally 2x will get higher performance and lower latency than powering 4x, but that can vary too based on DIMMS used.

    The 2x32GB C16 3200mhz is the fastest I've found in 32GB DIMM's, but there are C14 16GB DIMM's at even higher speeds.

    You'll have to do more digging for some owners reports, and / or test it yourself. Buy 2x16 / 4x16 at highest speed / Cas at best price and same for 2x32, and test it on your applications.

    You can always sell the memory you don't need / want to keep - or return it for a full refund - make sure there's no re-stocking fee for returns where you buy it - and do the testing quickly so you can return it within the return window - usually 7 days to 30 days.

    Please come back and let us know how it works out.
     
  9. jack574

    jack574 Notebook Consultant

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    Thanks. 3200Mhz is available but is hugely more expensive than 2666, so I've already decided to stick to 2666.

    If there's no noticeable difference in performance, makes sense to go for 2x32GB just in case I ever do want to upgrade to 128GB (I'd say extremely unlikely but you never know...)

    Thanks

    Thanks. Probably won't get the opportunity for testing, but my needs are photoshop editing (large files - I've maxed out the 32GB on my current laptop a few times) and 4k video editing. Also 3D CAD work.

    "Generally 2x will get higher performance and lower latency than powering 4x, but that can vary too based on DIMMS used." - that is just another case for 2 x 32 rather than 4 x 16.

    Looks like 2x32 is the way to go then. Thanks guys
     
    Last edited by a moderator: Dec 11, 2019
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  10. jotm

    jotm Notebook Evangelist

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    If you've maxed out 32GB, you will likely need more RAM sometime in the future :D

    Performance difference will not be noticeable, if at all different, assuming same clocks and timings.

    4K video work alone can eat up your 64GB, the processor used to be a bottleneck, but that 9850H is a beast and will handle it.

    Remember when 16GB was more than you'll ever need? Good times
     
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