I am building a new gaming/production computer this year and I have found some components that I want to add to the system. This is the list of components so far:

  • CPU: Intel Core i7 6700K
  • GPU: Asus GeForce GTX 1080 Strix Gaming OC
  • Case: NZXT H440W NE (Sort)
  • Motherboard: Asus Z170-DeluxeCorsair
  • PSU: HX1000i 1000W

However regarding the RAM I was unsure as to which one I should pick. The spec sheet for the i7 6700K says that the CPU supports RAM of up to 2133MHz. However the motherboard (being compatible with the 6700K) supports RAM up to 3466MHz.

So which limit should I respect here? The limit of the motherboard or the limit of the CPU?

I have heard from "untrustworthy" sources that it is the motherboard that decides which RAM speed I can use, but how does this work practically? I guess there must be a reason why Intel has listed 2133MHz as the upper limit of supported RAM speed, right?


2 Answers 2


I would look at the CPU RAM speed. The motherboard supports faster RAM because CPU's could come out that support faster RAM in the future. For now, getting faster RAM than you CPU can handle is wasting money as faster is usually more expensive.

However if money is no option, you can buy the quicker RAM, so when you upgrade the CPU in teh future and it supports quicker RAM, it will be utilised.

The motherboard can definitely detect at which speed to run the RAM regardless.

Intel lists that speed so you can't go back to them and say: "Hey, my RAM is only running xxx fast but its actually a yyy."

  • So let me get this right. If I go for a 3466MHz, the motherboard and CPU will support it, but the speed will be capped at 2133MHz because of the CPU limit?
    – Arete
    Jul 6, 2016 at 9:19
  • @Arete No; The motherboard will overclock the memory, in any event the listed memory frequency, isn't the maximum frequency the CPU supports.
    – Ramhound
    Jul 6, 2016 at 11:11
  • I understood literally nothing of that, sorry...
    – Arete
    Jul 6, 2016 at 22:14
  • @warhansen does using higher frequencies offers lower cas? Jul 2, 2022 at 8:32

Any above 2133MHz DDR4 RAM will work fine with that CPU, that's why that many types of multipliers and ratios exist.

Considering my DDR1/2/3 experience so far, I'd state that I will not buy DDR4 if it is below 3200MHz, since something like that will offer no extra performance in a random environment.

General factors to consider when getting RAM modules are: lowest timings, highest frequency.

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