Why not 2800MHz? why is 1600Mz better?

[toolmaker_03]

Ok so this is my question we have 2800MHz memory and processors that can get it there so why is it that 1600MHz memory is recommended for these new systems?
Is it a stability issue?
Is it actually slower?
What are the problems with this type of memory?

 

[dextermat]

Yep that's normal, you can achieve 2800 mhz if you overclock only.

Normal frequency for core i7 is 1600 mhz.

So unless you overclock: memory is overkill.

 

[Sakkura]

Lower-frequency memory is cheaper, and beyond 1600 MT/s the actual performance gains are generally not worth it.

 

[toolmaker_03]

So is it that the memory really is not stable at that speed, or is it that the hardware really is not there yet for that speed?

from what it sounds like the hardware is not there yet right?

 

[Sakkura]

Yeah as long as the motherboard and memory controller (be it on the CPU or not) are compatible it's stable. It's just not always worth it to maximize, since it apparently doesn't hold systems back all that much.

There are exceptions, for example if you're relying on an APU or other integrated graphics; they'll benefit more from faster memory (just like dedicated graphics card have much faster memory on board than what you plug into the motherboard).

 

[DJDeCiBeL]

So is it that the memory really is not stable at that speed, or is it that the hardware really is not there yet for that speed?

from what it sounds like the hardware is not there yet right?

From everything I've ever seen and read, it's basically down to the fact that the performance difference after anything faster than 1600 just isn't worth the extra cost.

The IMC's of current gen Intel CPU's, especially, love 1600 RAM, and that's where they're "happiest" at. The performance gained after that is so negligible (low single digit percentages, mostly), that it just doesn't make much fiscal sense to spend more money on anything faster. The same can be said for trying to OC RAM, as well. It's just basically pointless to do it.

I'm guessing Haswell and other future gen's will change that, though.

 

[amuffin]

Right now there is no performance difference between 1333mhz and 2800mhz.

 

[Sakkura]

Here's an example of the performance difference you can get in games with faster memory; 2133 MT/s compared to 1600 MT/s in this case:

Source article:
http://www.tomshardware.com/reviews/bulldozer-ddr3-overclocking,3209.html

 

[Maxx_Power]

So is it that the memory really is not stable at that speed, or is it that the hardware really is not there yet for that speed?

from what it sounds like the hardware is not there yet right?

At this point of time, all the good points made here thus far are correct. There is no need for the additional bandwidth, and the memory controller in existing CPUs can only support such a high frequency.

The memory controller in the AMD Phenom II, for example, needs to run optimally at a ratio of 3:1 to the base clock of the memory. So a 2000mhz memory controller (by default) can support comfortably and stably only 667mhz (rounded up) memory, which when DDR'd, goes to 1333. To reasonably run 2800, you need 1400x3 = 4200 mhz memory controller frequency, which is impossible currently on that CPU. So you have to use memory clock dividers. If you use memory clock dividers, you are essentially accessing the memory (which runs really fast) at only once every few available cycles, and thus the total bandwidth of the memory isn't really utilized by the CPU.

Another BIG reason why faster memory isn't adopted is due to the DDR3 architecture. This architecture of memory isn't designed for >2ghz operation, and thus silicon yields are low for higher binned DDR3's. This makes the availability of fast DDR3's an issue, and no manufacturer of CPUs would bet their flagship CPU on the ill-supply of top, top binned DDR3's because they are very rare and command a premium. For the money of 2800mhz certified sticks, you can probably get twice as many sticks of 1600mhz DDR3, thus why the LGA2011 CPUs support Quad Channel instead of Dual Channel. In the graphics world, this issue is solved with the introduction of GDDR5 (quad data rate memory). Something like this is coming circa Haswell or beyond with the next iteration of DDR-something or other.

 

[toolmaker_03]

Best answer selected by toolmaker_03.

 

[toolmaker_03]

thank you that helped a lot

 

[Maxx_Power]

thank you that helped a lot

No problem. Glad to help.