Question regarding DDR4 Freq Bus

ZikO

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Mar 5, 2010
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Could someone please explain which memory kit I should use for my new build:

https://uk.pcpartpicker.com/list/Tc3RCy

Basically, it is based on Intel i7 Core 7700K and ASUS z270 MAXIMUS HERO IX. I can read here that this processor can handle DDR4 upto 2400 MHz whereas the motherboard can support memory kits up to 4133 MHz Non-ECC un-buffered.

Should I buy something more than DDR4 2400Mhz or stick to 2400 Mhz only? I can see some people who also build new comps decide to go for memory kits with much higher bus freq than processors can handle, e.g. 3000 Mhz and more. Why is that? Is it purely for overclocking purposes?

Thanks
 
Solution
You have to enable XMP to get the advertised RAM frequency, otherwise all DDR4 RAM runs at 2133MHz.

Inte's official support is conservative and applies to all chipsets but your CPU and board will support any frequency up to around 4133 as you say. You will have to enable XMP to get your 2400MHz anyway, so may as well get a slightly higher frequency as it'll benefit you, but not by a huge amount.


I'd keep it simple and go for the exactly what you chose which is shown to be compatible with the board and with that CPU. Yes, those other speeds including 2400MHz is OC'd. Once they get past 2400MHz there really isn't too much of a discernible change. Faster memory can have an impact but after a certain point it's more about the amount than the speed.

Video editing? CAD? Extreme gaming?

Why not the 212 Evo or Cryorig H7 or some other cooler that allows for a second fan which can help with cooling. Not a HUGE amount but I preferred to have an option in case I wanted a second fan. Which I eventually installed.
 
You have to enable XMP to get the advertised RAM frequency, otherwise all DDR4 RAM runs at 2133MHz.

Inte's official support is conservative and applies to all chipsets but your CPU and board will support any frequency up to around 4133 as you say. You will have to enable XMP to get your 2400MHz anyway, so may as well get a slightly higher frequency as it'll benefit you, but not by a huge amount.
 
Solution
I came across XMP but did not realise I would have to set it on manually. This sounds like some form of OC because 2400 MHz that is what Intel recommends.

Just to be completely 100% sure, let's say I have bough 4133 MHz memory kit. Can computer be stable if I "downlock" system to let's say 3000 MHz? Are there any multiples I need to follow? 4133 MHz looks strange compering to 4000 MHz :)

Also Is bandwidth and bus freq related meaning if I increase one, the other increases as well?

I hope I am clear about what I am asking. I am rather newbie at this 😛

Thanks
 
With 4133Mhz RAM you have two options. 2133MHz or 4133MHz, unless you manually set all the timings which I wouldnt recommend. To enable XMP you literally just press a button in your BIOS. With 2400MHz RAM you have the choice between 2133MHz or 2400MHz.

I'd choose to get somewhere in between as those v high frequencies are a bit beta and can be a bit unstable. Somewhere around the 3000/3200MHz level would be best to buy.

Bandwidth is frequency, generally speaking. You wont really notice any difference between any of them. Most benchmarks basically show no difference, but with a good CPU ideally you want memory that can perform well with it.