DDR4 2800mhz Ram speed seems low.

[wade7575]

I just built a ASUS X99-A PC with Corsair DDR4 2800mhz Vengeance ram when I look in the Bios it say's it's running at 2133 and in ASUS Suite it say's 2159.2 for DRam Frequency.

I set the bios up to just run optimized default's as I decided not to overclock my i7 5920K as it's plenty fast for anything I want to do,I was just wondering if the new DDR4 does not always run at the speed it's supposed to unless set in the bios to run.

 

[EarthDog]

Optimized default is 2133, the base for that platform/cpu. If you want your memory to run at 2800MHz, enable the XMP profile.

 

[wade7575]

I should have known that as my last mobo had that same feature on it and I forgot to run it and it's one of those thing's I don't mess with at all because once it's set it set.

Thanks for the help.

I tried going into my Bios and I forget witch Profile used if it was 1 or 2 but the one I choose to run was the one that let's me run my Ram at 2800mhz.

But here's the problem when I do that it overclock's the CPU to 3.8ghz plus,I thought I could the ram at 2800mhz and not have to overclock the CPU or am I wrong on this.

 

[Woomack]

When you enable XMP profile then memory will run at 125MHz bclk. At least it happens in case of DDR4-2800. Because of limited memory ratios it's usually like:
2133, 2400, 2666 = 100 bclk
2800, 3000 = 125 bclk ( 100 also works on many motherboards at 3000 but not at 2800 )
3200 = 100 bclk

So if you don't want to overclock CPU then or change CPU ratio manually to lower or use memory ratio that requires 100 bclk.