I'm looking at two choices of 2x2048MB (4GB total in 2 sticks), dual channel PC6400,800mhz for an Asus pk5-e wifi . 1st one is rated with a timing of 5-5-5-18. The 2nd one has 4-4-3-15. The 2nd one is about $70 more.

I've also read an article showing that SUPER expensive DDR3 1333 gives no more than a 1% improvement over DDR 2 800mhz with all the programs tried in the article - http://www.digit-life.com/articles [...] -1333.html

So I'm kind of drawing the conclusion that getting the more expensive PC6400 in tighter timings won't help my system to be any faster. Especially if 1333mhz ram with high fsb can't help. Is it true then? Is there anything to gain by spending an extra $70 on the 4-4-3-15 timing?

First, what memory are you looking at? Someone here will recommend something better I'm sure.

I had asked for suggestions 2 days ago and was told that OCZ was a high quality brand. So that's what I searched for. Only some have tighter timings. I can believe that OCZ is high quality, but I don't think the lower timings will help, but could be wrong. OCZ Reaper Dual Channel 4096MB PC6400 DDR2 800MHz Memory is the description.

5-5-5-18 - http://www.tigerdirect.com/applica [...] CatId=3412

4-4-4-3 - http://www.tigerdirect.com/applica [...] CatId=3412

Yet another seems to be a favorite, but maybe because it looks golden, lol. It doesn't have a heat pipe. I wonder how important that is as well. But here it is - 5-6-6-15 - http://www.tigerdirect.com/applica [...] CatId=3412

another - 5-4-4-15 - http://www.tigerdirect.com/applica [...] CatId=3412

another - 4-4-4-15 - http://www.tigerdirect.com/applica [...] CatId=3412

Edit: I don't know if it will help, but I ordered the last one with 4-4-4-15 timings. It lacks a heat pipe, but it says it has a decent metal heat spreader. I hope I chose right.

Right so 4 - 4 - 4 - 15 kicks 9 - 9 - 9 - 27 in the face, right? Or is it the other way around? ...

lower figures = lower latency = better

Lower timings are faster. Is the difference worth the price? only you can decide.

However, this "Right so 4 - 4 - 4 - 15 kicks 9 - 9 - 9 - 27 in the face, right? Or is it the other way around? ..." is a "I don't know". Here you are comparing DDR2 timings with DDR3 timings at an unknown frequency.

I bought the parts for Box #1 16 months ago. Fast DDR2 memory was really expensive. Because I did not know how far I would be able to OC the various parts, I over spec'd the memory. I ordered DDR2-1000 memory and an AC 7 Freezer Pro HSF. (Yeah, I know. It's a mismatch.)

Memory defaulted to 5-5-5-15-2T timings at 1.9 volts. Specs say the D9 Micron chips could run at 2.2 volts. Bumped the mem volts up to 2.2 volts. The maximum stable OC (24 hour Orthos) I was able to reach was 3.3 GHz (367 MHz FSB - DDR2-667). I worked the timings down to 3-3-3-6-1T. Memory I/O increased about 7%. The improvements in the rest of the benchmarks were virtually insignificant. I am GPU limited at 3.1 GHz with a stock clocked 640 M GTS8800.

I upgraded my HSF with the TR Ultra 120 Extreme/S-Flex fan combo. I was able to push the E6600 to 3.6 MHz (400 X 9). 450 X 8 works at 4-4-4-12-1T but my MCP temps go past 85 deg. C.

I am running my memory at a relatively conservative 4-4-4-12-1T. 3-4-4-10-1T almost works; Orthos crashed at 18 hours.

In my case, the extra $70 that I spent really did not get me a real world performance gain. Of course, YMMV.

So anyway. The RAM you ordered looks good. I'm sure you'll be happy with it. And, heat really isn't an issue with RAM unless you go well above the voltage limit and even then good case airflow will do wonders.