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Installed ram is dual channel 2666 and 3200 but CPU Z showing only 665.5mhz aprox

Anonymous
2021-03-05T08:30:41+00:00

I have bought new laptop Dell inspiron 3501. This model support 2666 and 3200 mhz. There are total two slots availiable. In one slot i have installed samsung 3200mhz ram and in another slot it is 2666mhz ram. Now in task manager it shows 2666mhz speed. But when i check CPU Z application then it shows current DRAM speed is usable is only upto 665.5 aprox. Because i have installed two different ram so lowest speed should be considered i.e 2666 and because it is DDR it should show 1333 in DRAM in CPU Z. Why this is happening??????? I have fully updated my drivers, my bios and windows update. I am on windows 10 20H2 and os build is 19042.844

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  1. Neil D 32,830 Reputation points Volunteer Moderator
    2021-03-05T09:00:46+00:00

    This relates to motherboard hardware and not windows.

    To use dual channel they must be matched pair and these are not. They are probably being throttled by the motherboard for stability. Look at the difference in the Timing table and the modules are struggling to operate and if they did work at the higher speed (1333Mhz) then windows would probably crash all the time.

    If you want to use dual channel you need to match a pair of memory modules.

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  1. Anonymous
    2021-03-06T03:16:53+00:00

    Oops eh! I don't know why I said 1333 (maybe because of CPUz ?), but regardless, you said ...

    "In one slot i have installed samsung 3200mhz ram and in another slot it is 2666mhz ram."

    The motherboard may support both 2666 and 3200, but not at the same time. Mixing speeds won't damage your motherboard,

    but as has already been said, it will lead to problems.

    .

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  1. Anonymous
    2021-03-05T10:28:57+00:00

    Thanku for your reply. Please clear my doubt. In task manager the speed is showing as 2667mhz. Also my bios shows 2667mhz. But only cpu z shows DRAM 665.5 aprox and changing in decimals only. I have talked to Dell customer service but they told me cpu z is a third party application and he is not liable for that. They told me that your bios and task manager are showing 2667mhz and this is what speed you are getting. Please clear some of my ques

    1. Is CPU Z showing true value or task manager showing true value??????
    2. Is there any tool so i can check real-time ram frequency and memory bandwidth?????
    3. If I don't change my current configuration of ram then will it damage my motherboard anyhow????

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  2. Anonymous
    2021-03-05T11:45:21+00:00

    "In one slot i have installed samsung 3200mhz ram and in another slot it is 2666mhz ram."

    • As Neilpzz mentioned you cannot use two RAM modules with different speed, cas, or voltage without performance or instability issues.
    • The mismatch is likely what is causing the different reports, and is an illustration of why using different spec RAM modules confuses Widnows.

    DDR stands for double data rate, and CPUz shows half the total. In this case half the 1333MHz module, while Windows shows the full speed

    (doubled rate), and in this instance it looks like Windows looks to be focused on the 2666 MHz stick.

    Also note that the higher RAM speeds that a cpu\motherboard is 'capable' of are overclocking speeds.

    The best guarantee for stability and performance is to use the BIOS default RAM settings.

    While XMP speed is generally stable, there is no guarantee.

    While adding another RAM module that has the exact same specs as the original will generally work, RAM mfg's will

    only guarantee optimal performance and stability if you use a factory matched pair.

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