Regarding Ivy Bridge's 2800Mhz RAM support...

[psolord]

Hey guys.

I've been reading Anandtech's piece about Ivy Bridge's architecture, when I stabled upon the memory and overclocking part.

Intel's slide shows this:

The article's text below reads:

Memory overclocking also gets a bump in Ivy Bridge. The max supported DDR3 frequency in SNB was 2133MHz, Ivy Bridge moves this up to 2800MHz. You can now also increase memory frequency in 200MHz increments.

Now this brought up some questions.

First of all, Intel's own specifications regarding the 2600k for example, says that it supports DDR3-1066/1333.

Doesn't that DDR3-1066 translate to 1066X2=2133MT/sec due to the double data nature of the memory chips? So maybe that 2800 MT/sec of the slide, does not translate to 2800Mhz but DDR3-1400Mhz instead?

What am I missing?

Thanks beforehand!

 

[Ben90]

The confusion here lies with there being two different things that Intel supports. On the OEM and super stable side, Sandy Bridge officially supports up to DDR3-1333. They do however allow you to run your memory at up to DDR3-2133. The 2133 number is not officially supported, just the max that you will be able to select by using only the DRAM multiplier.

Its much the same thing as them changing the max CPU multiplier. Old unlocked CPUs could only go up to a 57x CPU multiplier, or 5.7GHz for SB without changing the BClock. Now we can select a 63x multiplier with IB yeilding a 6.3GHz clock rate on a 100Mhz BClock.

You did have a very good guess with a possible reason for the above being double pumped DRAM. When you purchase a kit labeled as DDR3-1333, it is already double pumped to achieve that number. So the actual bus is running at only 666Mhz.

Interestingly enough, even that slide forgets the differences between Hertz and transfers per second. The last bullet point should be changed to "Finer grain steps in adjusting frequency - Added 200 MT/s"

 

[psolord]

So my confusion was kind of justified at least...!

We are talking about 2800Mhz DDR3 indeed then. With 1400Mhz physical frequency?

Thanks ben!

 

[aviat72]

What kind of latency are we talking here?

 

[Idontcare]

capable != support

My 2600K is capable of a 57x multiplier, but using 57x multiplier is not supported by Intel.

Just because Intel has upped the dram multipliers such that it will now be possible to select DDR-2800 speeds does not necessarily mean Intel will support such configurations.

 

[AdamK47]

I like how the word "support" and "up from 2133" are used in the same sentence. Whatever could that mean?

 

[ElFenix]

I like how the word "support" and "up from 2133" are used in the same sentence. Whatever could that mean?

that tech writers don't proofread.

 

[The Ultimate]

I run my 2600K with DDR3 2,133MHz, it works fine, even though I don't see much performance gains compared to 1,866MHz.

 

[AdamK47]

I run my 2600K with DDR3 2,133MHz, it works fine, even though I don't see much performance gains compared to 1,866MHz.

Better watch out. It's only suppose to run with the memory at 1333MHz. It may spontaneously self destruct.

 

[The Ultimate]

Better watch out. It's only suppose to run with the memory at 1333MHz. It may spontaneously self destruct.

Don't scare me like that! :\ My mobo is a Gigabyte Z68X-UD4-B3 and I have the voltages tightly locked at stock to avoid any issues with the IMC, but if you know something that I don't, let me know.... :'(

 

[grkM3]

my latest bios on my mive board gives an intel watning the second you go past 1.65 volts.says something about it being the max safe volts for sandy and going over may cause damage to the cpu.

BUT up to 1.65 is ok.

 

[Ben90]

What kind of latency are we talking here?

Hard to tell. The memory controller and its connection plays a bigger role than an individual stick.

Going from relaxed DDR-2800@14's timings to an unrealistic DDR-2800@9's only knocks off 3.5ns from the memory response time. In comparison, Bloomsfield IMC takes around 30ns just to reach the memory.

 

[The Ultimate]

Nice, my RAM sticks are running at 1.51V, but the timings are kinda high, 11,11,11,30, but it scores about 40ns latency according to Everest 1.85.1600.

 

[Idontcare]

my latest bios on my mive board gives an intel watning the second you go past 1.65 volts.says something about it being the max safe volts for sandy and going over may cause damage to the cpu.

BUT up to 1.65 is ok.

I believe you meant to say "up to 1.65 is ok...with my mobo maker, who isn't financially responsible for replacing my CPU if I toast it by running the Vdimm above Intel's upper spec limit of 1.57V"...right?

My Mive-z has not qualms about defaulting my 1.5V memory at 1.65V, actually taking my memory out of spec in addition to my CPU. If my ram dies, or my cpu, it won't be GSkill's fault or Intel's fault.

It will be Asus fault, but they aren't about to start caring because they will just turn you away if you go after them for a hardware damage claim. (they limit their liability to that of replacement cost for the mobo itself, if it burns down your house that's on you, if it takes out your cpu that's on you)

But I like this philosophy that just because some random pop-up occurs in your BIOS that you are suddenly "in the clear" to do whatever the random pop-up claims is ok. Sounds like a recipe for doing some monumentally stupid things our of ignorance. Who would ever believe some 3rd parties interpretation of the spec on your hardware when you have Intel's spec at your disposal?

 

[Dadofamunky]

Nice, my RAM sticks are running at 1.51V, but the timings are kinda high, 11,11,11,30, but it scores about 40ns latency according to Everest 1.85.1600.

That seems about right for DDR3-2133.