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  1. #1

    Default RAM choice - higher freq or lower latency?

    I'm interested in the community's thoughts on RAM.

    I've got my choice pretty much narrowed down to 2 nearly identical sets of G.SKILL Ripjaws V Series 32GB (2 x 16GB) 288-Pin DDR4 SDRAM. The only difference is 3600MHz and CAS 16 vs 3000MHz and CAS 14. They're basically the same price. I'll pick up 2 kits (4x16GB for 64GB total).
    DDR4 3600 (PC4 28800)
    Timing 16-19-19-39
    CAS Latency 16
    DDR4 3000 (PC4 24000)
    Timing 14-14-14-34
    CAS Latency 14

    I'm running a mildly overclocked i9-9900k, on an ASRock Z390 Phantom Gaming 4 motherboard. The MB says it will support up to 4300MHz, but anything over 2666MHz is considered an overclock.

    Neither SKU actually appears on my MB's supported page (, but they do support similar capacities/timings/frequencies. I acknowledge that I'm taking a bit of a roll of the dice either way. But the MB is ~2 years old, and these are newer RAM SKUs. So I think I'll be OK, but if anyone sees something I'm missing, let me know.

  2. #2


    Is not an either/or.

    CAS latency is measured in the number of clock cycles, so the latency is dependent on the frequency.

    You can convert to nanoseconds to get absolute latency.
    The F4-3600C16D-32GVKC kit has CAS latency 16 and frequency 1/3600, multiply to get 4.444 ns absolute latency.
    The F4-3000C14D-32GVR kit has CAS latency 14 and frequency 1/3000, multiply to get 4.667 ns absolute latency.

    So the F4-3600C16D-32GVKC is faster and more responsive.

    However, regarding the QVL, your AsR Z390 Phantom Gaming4 is listed on the G.Skill product page for the F4-3000C14D-32GVR (see but not for the F4-3600C16D-32GVKC.
    Last edited by Wizeowel : 09-03-2020 at 08:44 AM

  3. #3


    Thanks for that. Soon as you said it I realized I had totally forgotten about multiplying out the latency. Been too long since I actually had to build my own rig. I went with the 3600MHz, should arrive this week.

  4. #4


    I havent bothered to learn how the RAM latency etc work in fine detail, but what i noticed is that going from 3000 to 3600 = my main game "sustained fps" increased by around 7-10. Using the xmp bios profile. *your milage may vary.
    Last edited by WOWBOX40 : 09-08-2020 at 08:28 PM
    (usually chronically bad at finishing a post, please hold for some minutes.... before you reply / quote it, as i might be editing it)

  5. #5


    Just to close out this thread I went with the F4-3600C16D-32GVKC kit, everything is working fine - XMP is enabled although I have everything at stock speeds and voltages. Although I ordered 2x 32GB kits (4x 16GB sticks total) and ended up putting 1 kit in my wife's PC - so now I'm ordering 2 more kits.

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