Clueless on tweaking latency/tighter timings

[Abunai]

Im looking to get the most out of my cheapo G.Skill 512x2 kit (2.0-3-3-6 DDR400). After reading Zebo's thread I figure I should go for tighter timings first and keep my ram around 200mhz. What values/combinations should you focus on when going for tighter timings? Or to put it another way assuming Tcl will stay at 2.0, between Trcd, Trp and Tras what will have the bigger impact on performance?

 

[Amaroque]

2-2-2-5 1T will give you the best performance. You however do not say what CPU, or MB you are using. I'm assuming an A64 of some type, per your reference to Zebo's memory thread.

Are you overclocking? What speed (in MHz) are you running the RAM at? More info would be helpful.

 

[bjc112]

More info is def. needed.. But if it is an A64, keep in mind Speed (Mhz) tops everything..

So higher speed > Timings

 

[Abunai]

Forgot to make a sig, there ya go.

Originally posted by: bjc112
More info is def. needed.. But if it is an A64, keep in mind Speed (Mhz) tops everything..

So higher speed > Timings

I was under the impression it was the other way around, at least from Zebo's Memory Matrix thread. Unless you're referring to CPU speed?

Right now I just have a modest 2.4ghz OC using a 166 divider (10x240). The ram is still at the default 200mhz in dual channel.

I think my biggest source of confusion regarding timings is the Tras value (the one that goes up higher than the others) and how it affects Trcd and Trp. What would be the difference between 2-2-2-7 and 2-2-2-5 for example?

 

[Diogenes2]

Originally posted by: Abunai
What would be the difference between 2-2-2-7 and 2-2-2-5 for example?

Probably nothing you could measure...

 

[hmmzzz]

That last number doesnt do much for performance...i get slightly higher benchscores (when i say slightly, i mean slightly) when i set it to 10 instead of 5, but i think ive read somewhere that that last number has something to do with compensating for inconsistencies of your memory or something....

I'm curious about it myself now...will look it up

 

[Abunai]

Appreciate it hmmzzz.

Between Trcd and Trp, if one had to stay at 3 in order to maintain stability does it matter which one (ergo 2-3-2-6 or 2-2-3-6) gets bumped down?

 

[Shimmishim]

here is a good thread for you...

http://www.xtremesystems.org/forums/showthread.php?t=48634

 

[hmmzzz]

^^ interesting thread indeed ^^ I wonder how much effect a higher FSB with a lower multiplier would have at same clock speeds...

 

[bjc112]

Originally posted by: Abunai
Forgot to make a sig, there ya go.

Originally posted by: bjc112
More info is def. needed.. But if it is an A64, keep in mind Speed (Mhz) tops everything..

So higher speed > Timings

I was under the impression it was the other way around, at least from Zebo's Memory Matrix thread. Unless you're referring to CPU speed?

Right now I just have a modest 2.4ghz OC using a 166 divider (10x240). The ram is still at the default 200mhz in dual channel.

I think my biggest source of confusion regarding timings is the Tras value (the one that goes up higher than the others) and how it affects Trcd and Trp. What would be the difference between 2-2-2-7 and 2-2-2-5 for example?

Ya..

CPU Speed > memory speed > timings..

Or so it seems..

 

[Amaroque]

Originally posted by: bjc112
CPU Speed > memory speed > timings..

Or so it seems..

I'd have to say it would be something like 80% CPU speed, 10% RAM speed, 10% RAM latancy. This is assuming you always keep the RAM above 200 MHz.

From my own tests, I know that 200 MHz 2-2-2-8 1T is faster than 250 MHz 3-4-4-10 1T
most of the time (CPU speed being constant). YMMV

 

[Abunai]

Originally posted by: Shimmishim
here is a good thread for you...

http://www.xtremesystems.org/forums/showthread.php?t=48634

Thanks for the link but that analysis seemed a little skewed IMO. Zebo makes a more direct comparison between high bandwith/loose timings vs. regular bandwith/low latency. Of course if you can achieve insanely high bandwith and low latency thats the best of both worlds, but I doubt I'll have my cake and eat it too with this particular ram. Hence my focus on LL.

 

[Shimmishim]

i thought the question was which value has the biggest impact on performance.... trcd, tras, etc...

 

[Abunai]

Originally posted by: Shimmishim
i thought the question was which value has the biggest impact on performance.... trcd, tras, etc...

It was, sorry I kind of went off on a tangent there. Honestly that thread doesn't answer that question very well either IMO. Trp (row precharge time) isn't even focused on, and there aren't many combinations tested in general to give a good comparison to. Just sayin, I appreciate the link though.

 

[bjc112]

Originally posted by: Amaroque

Originally posted by: bjc112
CPU Speed > memory speed > timings..

Or so it seems..

I'd have to say it would be something like 80% CPU speed, 10% RAM speed, 10% RAM latancy. This is assuming you always keep the RAM above 200 MHz.

From my own tests, I know that 200 MHz 2-2-2-8 1T is faster than 250 MHz 3-4-4-10 1T
most of the time (CPU speed being constant). YMMV

Mine sure isn't...

With 2-2-2-5 1T @ DDR 410 @ 2800mhz I was pulling about 28min in SuperPI

@ 3-4-4-8 1T @ DDR 518 @ 2800 mhz I pulled down 26:52

Sandra scores ( which mean nothing ) went up to 7100 from about 5900..

Just some quick scores..

3dmark 2k1 scores increased as well.. about 26000 to about 28560 or so..

 

[imported_Otter]

This whitepaper from Corsair explores the relative impact of the five most frequently cited timings.
http://www.corsairmemory.com/corsair/pr...1_Latency_Settings_and_Performance.pdf