Oh, I'm Soo Confused about latencies and timings

[Longspeak]

I have tried to research memory latency/timing importance on this forum, and mostly get that they are mostly insignificant???? I clearly don't understand latency/timings!

None-the-less, my question is for Giga-Byte P55 MB, I5-750, RUNNING AT DEFAULT SPEED WITHOUT OVERCLOCKING. Which of following is best, or do I just buy on lowest price for quality manufacturer? If no real detectable difference in use, theoretically which is best?

memory latency timings
1333 7 7 7 7 21
1333 8 8 8 8 21
1600 9 9 9 9 24 2n
2000 9 9 9 9 27 2n

I suspect that if I'm running motherboard at 1333, then the 1333 7 7 7 7 7 21 is theoretically best????

Thanks for the help

 

[Swivelguy2]

With the i5-750, the highest you can turn the memory speed is 10x the BCLK, which is 133 MHz at stock, so the highest memory frequency you can run without overclocking the CPU is 1333 MHz. Given that, the lower the timings, the better.

 

[ChaiBabbaChai]

1600 9-24 gives a little bit more memory bandwidth than 1333 7-20. In other words, higher clock speed increases bandwidth, and so does tighter (lower) timings.

see this article: http://www.xbitlabs.com/articles/memory/display/ddr3-1600-lga1156_4.html

 

[Bill Brasky]

I'm pretty happy this thread happened because I haven't bumped my i5 to 1600 yet, and was wondering how much performance I'm missing. Looks like not much.

"And this is where we see very clearly that in real life things are completely different from what we have just seen in synthetic benchmarks. In many cases fast DDR3-1600 memory provides only an imaginary advantage over DDR3-1333 and DDR3-1067 platforms: very often the results differ by less than 1%. Very often, but not always. For example, we see in the multi-threaded test that faster memory may still have a noticeable effect on performance. By raising the DDR3 SDRAM frequency only one step higher we can increase the system performance by the good 4-6%."

 

[Longspeak]

1600 9-24 gives a little bit more memory bandwidth than 1333 7-20. In other words, higher clock speed increases bandwidth, and so does tighter (lower) timings.

see this article: http://www.xbitlabs.com/articles/memory/display/ddr3-1600-lga1156_4.html

Thanks for pointing us to this article-great analytical info with real world conclusions.

 

[Whisper2]

I have a Gigabyte P55-UD4P with 2 x 2GB OCZ Gold 1600 8-24. I originally was going to buy 1333 but on the day I bought, Neweqq had a relatively better deal for the 1600. I have used them at 1066, 1300 & 1600. I do not notice a difference in everyday performance.

Contrary to what you may read, the Gigabyte BIOS (at least for my model) does allow a memory multiplier of 12 (1600). (I know that Intel officially supports 1333 max but Gigabyte obviously has a different position.) The BIOS also will adjust timings and mem voltage without user intervention. At 1066, it sets the timings at 7 (I don't remember the final timing) @ 1.52V. These settings are consistent with the SPD. The SPD does not include settings for 1333 nor 1600, so the BIOS handles these itself. At 1333, it holds at 7-19 @ 1.568V, and at 1600, it eases the timings to 8-? @ 1.616V.

I finally selected 1333, because it seemed to offer the best combination of frequency, timings & voltage. My system has been running happily for the last several months with these settings.

 

[n7]

1600 9-24 gives a little bit more memory bandwidth than 1333 7-20. In other words, higher clock speed increases bandwidth, and so does tighter (lower) timings.

see this article: http://www.xbitlabs.com/articles/memory/display/ddr3-1600-lga1156_4.html

Excellent link to a great review!

Contrary to what you may read, the Gigabyte BIOS (at least for my model) does allow a memory multiplier of 12 (1600).

That's not a motherboard dependent scenario, it's a CPU-dependent one.

For stock systems:
i7 860 supports up to 12x multi (DDR3-1600)
i5 750 support up to 10x multi (DDR3-1333)

Edit: Apparently it is possible to have 12x RAM multi for the i5 750, but it's rare; generally they have the BIOS set to allow 12x for i7 860 & 10x for i5 750 due to stability issues according to the latest AT mobo review...

I know for the UD3R i have it's 10x only for i5 750 (12x for my i7 860).

 

[kithylin]

it all depends if you want to do overclocking or not. If you're not overclocking, you won't see any difference in 1600 ram @ 7ns than 1333 ram @ 9ns in day to day applications.

In my system, i HAD to go to 1600mhz ram to get my i7 up to 3800mhz because the lowest memory setting in bios makes the ram run at 1421mhz, so i couldn't use 1333mhz ram and the next up was 1600, so ended up with that, even if it's just running at 1421mhz.

 

[ChaiBabbaChai]

Thanks for pointing us to this article-great analytical info with real world conclusions.

Excellent link to a great review!

Yes indeed. It's always good to check xbitlabs.com for new articles