Timings vs. MHz

[18 is # 1]

Since the question/misperception of timings vs. speed (MHz) is frequently asked/misstated, I wanted to start a thread to give a simple example of why speed is most important. I will keep my comments directed to those of us who run Intel processors and chip sets with DDR2 since that can keep the generalizations from being too generalized.
Theoretically the same FSB will work with RAM to create the same performance such as this:
475 FSB 4-4-4-12 1:1 ratio 950 MHz tRD 12


And this 475 FSB 5-5-5-15 5:6 ratio 1140 MHz tRD 12

And as you can see the differences are not great.


BUT-
The looser timings allow is the tRD or Performance Level (PL) to be lowered, allowing significant gains in bandwidth: 475 FSB 5-5-5-15 5:6 ratio 1140 MHz tRD 8

Read, Copy, and Latency all improve and SuperPi gains .08 seconds which is almost a half cycle (counting to 1M).
My old Abit Pro mobo changed the tRD automatically and didn't provide an option for manipulation.
I haven't found many who don't gain from increasing their RAM speed. "Real World" results depend upon your applications, but empirical results are almost uniformly positive.

More on tRD here: http://www.ocztechnologyforum.com/fo...ad.php?t=36361

[Xello]

Good old tRD!

There's a page on Anand's QX9650 article when penryn launched back in Dec 07 which talks about it too:

http://www.anandtech.com/cpuchipsets...spx?i=3184&p=8

[twilyth]

It might be worth pointing out that any gain you get from tighter timings tends be diluted as the number of sequential words of memory retrieved increases.

I don't know how that goes for real world apps, but i've always assumed that things like reading a file or encoding video would access big chunks of memory at one time and that therefore speed would be more important that timing.

am i close?