DDR3 RAM 800 mhz running at 667 mhz. it's supposed to be PC312800 not 10700

rogalanr · Oct 11, 2017

Hi.

Well, I've read a lot of answers in your forum about this but in my DELL XPS 8700 I can't tweak my RAM or at least I don't know how.

Recently I bought two modules of this RAM ( https://www.newegg.com/Product/Product.aspx?Item=N82E16820313905 ) thinking it would be great for my computer but I realized my old modules worked at 800 mhz. and this new ones at 667 mhz.

In other thread about this kind of problem I found something about JEDEC speed and I can see that in my AIDA64 and CPU-Z Monitor and they are different but, then again, this RAM it's, supposedly, PC3-12800 1600 (800 mhz.). Please Help

One of my old modules are Nanya and I can see that this runs faster in my CPU-Z but, again, I can't move anything in my MOBO (which is model 0KWVT8).

Now I've seen some problems at my PC with mouse speed lag when I start an app (adobe, etc.) and I thought it was my browser (cause it was a clean windows install after the new ram) and some problems that I did read about, then I tested my modules with MEMTEST86 and no errors after 9 hours test... I don't know if there's something I could do or maybe buying same team memory or what.

Please Help! What can I do?

Thanks.
R.

EquineHero · Oct 11, 2017

rogalanr :

First off - you've got the terminology wrong. DDR3 is termed at 1600MHz and 1333Mhz, not 800MHz and 667Mhz. Those are DDR2 speeds.

Second - your motherboard only supports DDR3 at 1333MHz and below (to 1066MHz). That's why your RAM is at a lower speed - the memory controller automatically adjusts the speed.

rogalanr · Oct 11, 2017

EquineHero :

Hey, thanks for your answer... the thing is that, when I was only using the Nanya sticks and one Crucial Technology, the computer was running at 1600 Mhz. Then with the Team Vulcan I saw the difference between both at the same time and the motherboard adjusting.

Yesterday, I was reading about Cas Latency and the old ones has a wider range of clock timing (is that term correct) than my new ones:

Nanya

Maximum 11-11-11-28 (@800Mhz)

Team

Maximum 9-9-9-24 (@667Mhz) / 10--9-9-24

I found something about JEDEC too, but I'm not sure if that's something that define the way my RAM works... At Dell XPS 8700 manual don't say anything about only supporting 1333 Mhz. It reads1600 Mhz DDR3

EquineHero · Oct 11, 2017

rogalanr :

EquineHero :

Hey, thanks for your answer... the thing is that, when I was only using the Nanya sticks and one Crucial Technology, the computer was running at 1600 Mhz. Then with the Team Vulcan I saw the difference between both at the same time and the motherboard adjusting.

Yesterday, I was reading about Cas Latency and the old ones has a wider range of clock timing (is that term correct) than my new ones:

Nanya

Maximum 11-11-11-28 (@800Mhz)

Team

Maximum 9-9-9-24 (@667Mhz) / 10--9-9-24

I found something about JEDEC too, but I'm not sure if that's something that define the way my RAM works... At Dell XPS 8700 manual don't say anything about only supporting 1333 Mhz. It reads1600 Mhz DDR3

Then your problem is timing incompatibility. The timings between the Team and Nanya sticks is too different, so the memory controller slows the faster one down to match the slightly slower one. It's got to match the timings for each channel and does that by lowering the clock.

rogalanr · Oct 11, 2017

So then, why selling memory sticks at 1600 Mhz if they're going to run slower? I mean, it's that a good thing? Selling something DDR3 running at DDR2 speed?

It would be better to stick with only the Team's sticks or what happens here?

EquineHero · Oct 11, 2017

rogalanr :

They sell memory at 1600Mhz because you're supposed to match timing with identical sticks.

Say you had two of the same stick - there would be no compatibility issues because each stick runs at the same exact clocks and timings.

Because you have two different sticks with different timings, the memory controller has to adjust it so they operate on the same level.

I've got two Avexir Core Series 1600Mhz DDR3 sticks. Say I took one out and put in a Corsair XMS3 1333 stick, the remaining Avexir stick would downclock to match the Corsair stick's speed and timing.

You're reading clocks wrong. On 1600MHz DDR3 each chip is clocked at 800Mhz, but since 99.999% of DDR3 is double sided that bandwith is doubled, so an 800MHz chip clock is effectively 1600Mhz, and a 667Mhz chip clock is effectively 1333Mhz.

Same goes for double sized DDR2 sticks - a 400MHz chip clock is effectively 800Mhz.

All RAM is rated by effective clock. PC2 6400U is 800Mhz, PC2 5300U is 667.

DDR3 10600U is 1333, DDR3 12800U is 1600Mhz, and so on.

Look at this: https://en.wikipedia.org/wiki/DDR3_SDRAM

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DDR3 RAM 800 mhz running at 667 mhz. it's supposed to be PC312800 not 10700

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