Timings vs Frequency/mhz

[Nordland]

I've dabbled on the science of memory, but it still seems unclear from my own personal experience as to which is more important, my ram now 1600mhz at 7-7-7-20 timings is great, but still dosen't compare to my xmp setup of my old 2133 mhz @ 9-11-9-27.
What is a rule of thumb for actually weighting the performance of memory, because honestly I feel like half of the people building computers don't have a clue.
Cheers.

 

[imomun]

Normally its the MHz that defines performance.
But lower cas also matters. Example : Cas 7 1600mhz will be some or less cas 9 1866MHz performance.
Your OLD XMP 133 mhz @ 9-11-9-27 is the best setting

 

[rolli59]

We can call it science but really what it is what is acceptable to most. Running benchmarks will show the 2133 ram faster and specifically if it is memory performance benchmark. Then if you run application benchmarks there is a slight measurable difference but not at all noticeable.
If you are into record breaking at any cost the fastest ram helps but just for the pleasure of having a well performing system the fastest reasonable priced ram that is supported by your hardware makes the most sense. Remember well over 90% of computer users do not have a clue how to setup these extreme ram modules or overclock anything.
Good read on it http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3

 

[geofelt]

Good post from rolli59^

 

[RetiredChief]

2nd that
While that post from anandtech is mid 2011 it is still valid. Reason I bring that up is that they did not mention that DDR3-1600 voids the warranty for a SB CPU. For OCers, not a biggy as everyone knows OC voids warrantee, But not many know that DDR3-1600 Ram also voids the warranty for a NON OCed SB CPU. Solution was buy the Intel OC warranty (think it was 20->25 bucks). For IB ddr3-1600 is spec and anything over voids the warranty for IB CPU

PS My i5-2500K (OCed 4.2) uses DDR3-1600 CL7 @1.60 V and has been running great - Bought when i5-2500k first came out. ONLY mention as on the OUT change you have to RMA the CPU, Intel will most likely ask about memory.

 

[James Mauro]

I've dabbled on the science of memory, but it still seems unclear from my own personal experience as to which is more important, my ram now 1600mhz at 7-7-7-20 timings is great, but still dosen't compare to my xmp setup of my old 2133 mhz @ 9-11-9-27.
What is a rule of thumb for actually weighting the performance of memory, because honestly I feel like half of the people building computers don't have a clue.
Cheers.

Its very simple math to figure out which one is better giving that the size in gb's is the same.
for ddr3 (Cas latency/(mhz/2)) *1000
once again you need to divide the cas latency by half of the MHZ of the DDR3 memory than multiply the whole equation by 1,000 the number you see is in nano seconds and the lower the number the better.
In your case
1600mhz cas 7 (real Mhz is 800) (7/800)* 1000=8.75ns
2133 mhz cad 9 (real Mhz is 1066.5) (9/1066.5)=8.438819 As you can see in this case the faster MHZ one is better but not all are the same. Also If I by ram I would get a better quality each of the numbers are differenty latencies. I would typically suggest manufactures that give you all of the timing instead of just the first number. The lower the number of cas the better.

in ddr5 it will be the same equation but you will double the MHZ instead of dividing

so for ddr5 (cas#/MHZ#*2) * 1,000 and once again the smaller the number the better

And the higher percent of change the more noticeable improvement. If you compare 2,000mhz ram with 2133 mhz ram both with the same timing the percentage of change will be very small. If your computer cannot do the lower timing or the increase in mhz it will be for nothing.