DDR4 RAM - what speeds can we expect?

[Fjodor2001]

So soon the PC market will move to DDR4 RAM, with Haswell-E / Skylake and beyond.

What speeds can we expect a few years from now? I.e. at what speeds will DDR4 be initially, and what speeds can we expect to be reached within ~1-3 years of that?

Also, since DDR4 is point-to-point, what do you think will be the most common setup - 2 or 4 slots? And will all motherboards support 4 point-to-point slots?

 

[lamedude]

Quick look at JEDEC DDR4 PDF it looks like only up to 2400MT/s is defined with TBD in the 2666 and 3200MT/s columns. 4266MT/s is the goal.

 

[Fjodor2001]

Isn't it strange that they set the max DDR4 speed to 2400MT/s, which is less than current DDR3 max rates that are at 3000MT/s? I know you said the goal is 4266MT/s, but still.

 

[ShintaiDK]

You confuse stock and OC speeds Fjodor2001. That memory you link is already 1.65V at 2400 for example, just to make it even worse. And its 1.35V chips?

 

[mikeymikec]

Usually the 'next-generation' RAM starts off with an offering at the same speed as the fastest current-generation official speed, eg:

DDR2 started off at PC2-3200, matching the I/O clock of PC-3200 (DDR400) RAM (despite the existence of DDR-533).
DDR3 started off at PC3-6400, matching the I/O clock of PC2-6400 (DDR800) RAM (despite the existence of DDR2-1066).

Based on that, I'd guess that DDR4's slowest available official speed will match the I/O clock of DDR3-1866.

As for the fastest speeds, I can't see an obvious link between the highest and lowest speeds for a given generation of memory, so my guess is that it's based on as far as they can take the silicon at the given voltage for that generation.

 

[Fjodor2001]

You confuse stock and OC speeds Fjodor2001. That memory you link is already 1.65V at 2400 for example, just to make it even worse. And its 1.35V chips?

I don't think so. Actually it's 3000MT/s at 1.65V, see:

http://www.gskill.com/en/press/view/g-skill-releases-the-world%E2%80%99s-fastest-ddr3-32gb--8gbx4--memory-at-3000mhz-extreme-speed-designed-for-4th-gen-intel%C2%AE-core%E2%84%A2-processors-and-z87-motherboards

It's over the DDR3 specification's 1.5V limit though if that's what you mean. As for when overclocking the RAM I linked to out of the manufacturer's specified 3000MT/s limit, some have reached 4400MT/s with it! But that's another story.

 

[lamedude]

JEDEC DDR3 only goes up to 2133MT/s hence the need for XMP to run those overclocked speeds.
There is a DDR4-1600 defined but like DDR3-800/DDR2-400/DDR-200 it probably won't see much use.

 

[ShintaiDK]

I don't think so. Actually it's 3000MT/s at 1.65V, see:

http://www.gskill.com/en/press/view/g-skill-releases-the-world%E2%80%99s-fastest-ddr3-32gb--8gbx4--memory-at-3000mhz-extreme-speed-designed-for-4th-gen-intel%C2%AE-core%E2%84%A2-processors-and-z87-motherboards

It's over the DDR3 specification's 1.5V limit though if that's what you mean. As for when overclocking the RAM I linked to out of the manufacturer's specified 3000MT/s limit, some have reached 4400MT/s with it! But that's another story.

Now tell me, how much in that chart can keep up with standards?

Not to mention the chips used are 1.35V. You really gotta hate your data to use these kits.

I am sure you can quickly find some overvolted and overclocked DDR4 4000-4500 kits after release.

 

[Fjodor2001]

Usually the 'next-generation' RAM starts off with an offering at the same speed as the fastest current-generation official speed, eg:

DDR2 started off at PC2-3200, matching the I/O clock of PC-3200 (DDR400) RAM (despite the existence of DDR-533).
DDR3 started off at PC3-6400, matching the I/O clock of PC2-6400 (DDR800) RAM (despite the existence of DDR2-1066).

Based on that, I'd guess that DDR4's slowest available official speed will match the I/O clock of DDR3-1866.

As for the fastest speeds, I can't see an obvious link between the highest and lowest speeds for a given generation of memory, so my guess is that it's based on as far as they can take the silicon at the given voltage for that generation.

Yes, so the question is what DDR4 speeds we can expect in ~3 years time or so. Is the 4266MT/s limit you mentioned a hard limit according to the DDR4 specifications? Or is it just what they expect some DDR4 RAM to reach not too far from now, but it's something that can be exceeded going forward?

Also, since DDR4 is point-to-point, let's say you have have four DDR4 RAM modules each at 4266MT/s and compare that to current 2133MT/s DDR3 RAM. Then you'll effectively get a 2x speed boost from the frequency increase alone, but also a 4x speed boost from there being 4 modules to fetch data from in parallel as I understand it. I.e. effectively a 2x4=8x performance improvement in total. Is that correct, or am I missing something?

 

[Fjodor2001]

Now tell me, how much in that chart can keep up with standards?

Not to mention the chips used are 1.35V.

I am sure you can quickly find some overvolted and overclocked DDR4 4000-4500 kits after release.

Nothing in that post contradicts what I said in my previous response to you. I said it exceeds the 1.5V DDR3 specification and requires 1.65V, but can reach 3000MT/s while doing so according to the manufacturer. It can also be overclocked above that, and some have reached 4400MT/s.

 

[ShintaiDK]

It even exceeds the 1.35V specifcation. Since these are 1.35V chips, if not even 1.2V.

DDR4 will be faster on spec speeds from day one due to DDR4 2400.

And nobody knows what DDR4 will overclock to.