I am a little confused here...

[NoiseKraft]

I just ordered a i7 5820K and 2666MHz G Skill Ripjaw Memory.

Whilst looking at a few i7 5820K reviews I noticed that some specs said that it only does memory types DDR4 1333/1600/2133 not 2666MHz

Is this old information or have I just ordered wrongly or wtf.

Krafty.

 

[wazza300]

You should be able to run 2666mhz and higher,they don't list all the frequencies, idk why

 

[Rroff]

^^ Official support is upto 2133 anything over that Intel considers "overclocked" and hence don't guarantee support so it isn't listed. Shouldn't be an issue but you might find the IMC won't handle it on weaker examples of the CPU.

 

[DragonQ]

Yeah the same is true with pretty much all CPUs. The Core i7-920 only officially supported up to 1066 MHz DDR3, yet most people at the time bought 1600 MHz RAM. Same for the budget Celerons and Pentiums - rated for 1066 MHz but work fine at 1333 MHz (at least).

 

[Justintime]

Yep, also some memory speeds are 'unofficial' as theres no JEDEC spec for it hence compatibility can't be ensured. Most of the time these speeds will become official later on.

 

[mmj_uk]

It's basically that memory and motherboard manufacturers still try and sell their products to people based on maximum supported memory speeds (the higher the better!) even though the memory controller is now built into the CPU and is usually much less than the memory/motherboards in which manufacturers sell.

It's like Rroff says you'll still be able to able run your 2666 memory at 2133 but anything above that is overclocking, will likely need voltage increases and is not guaranteed to be stable.

 

[ginjaninja]

the difference in performance with different memory speeds is not significant, so although no one wants to pay for something there not using, your not missing out in performance terms.

cpu-z will tell you what speed your memory is running at, you may need to tweak a bios setting to get it use the overclocked memory profile on the spd of the memory.