Quick Memory Lesson

[Joe DeFuria]

OK,

I'm building a P4 3.0c machine, and will be buying 1 Gig of memory. (2 512 MB modules for dual channel.)

Questions regarding "the best" memory to buy...

If I completely disregard any overclocking at all, I'll just want PC3200 memory with as low latency / aggressive timings as possible. (2-2-2 I presume is essentially the most aggressive / supported)

On the other hand...

If I'm thinking about overclocking, the best bet is to "match" the rated speed of the ram, with the anticipated FSB overclock. In other words, if I believe can overclock the FSB to (100+9)*4 = 437 Mhz, I should get some PC 3500 rated memory, with the lowest rated timings.

The caveat being, if I understand correctly, is that if I'm not successful in overclocking, running PC3500 at 3200 speeds is not only an obvious waste of money, but could actully be slower than 3200 memory, because the timings may not be as aggressve.

Is that about correct?

So basically, say I have the following choices
1) PC 3200, 2-2-2 - baseline price
2) PC 3500, 2.5-4-4 - a little higher price
3) PC 3500, 2-2-2 - significant higher price

Specific questions:
A) Option 2 will be slower than option 1 running at FSB 400 speeds.
B) Is it even possible / likely that the less aggressive timings might make option 2 even a worse performer at 437Mhz FSB, compared to 1 @ 400Mhz FSB?
B) The only disadvantage of option 3 vs. option 1, is price, correct?

 

[AAlcHemY]

1) PC 3200, 2-2-2 - baseline price
2) PC 3500, 2.5-4-4 - a little higher price
3) PC 3500, 2-2-2 - significant higher price

B) Is it even possible / likely that the less aggressive timings might make option 2 even a worse performer at 437Mhz FSB, compared to 1 @ 400Mhz FSB?

Not worse, its a Intel rig. Amd is far more timings dependant.

B) The only disadvantage of option 3 vs. option 1, is price, correct?

Indeed.

( And harder to find, those modules mostly use BH-5 chips. Most PC3500 and up use CH-5 chips, but they cannot run low timings. There are a few others, Hynix for example, but there more budget. )

In your place, i would go for the 3200 - BH-5. Simply because its basicly the same as good PC3500.

 

[Joe DeFuria]

Thanks!

So then, here's the $120 question.

For this intel rig, I can go with something like (opposite ends of the price / performance spectrum)

1) 2x512 MB, PC3200, 2.5-4-4 timings, $170
or

2) 2x512 MB, PC3500, 2-2-2 timings, $288

Anyone have thoughts on whether the extra $120 is worth it?

 

[AAlcHemY]

Dont buy the first one.
And that Mushkin 1GB PC 3500 Level 2 Dual Pack is a bit expensive imo. ( Although, i payed 500€ for 2x 512Mb XMS Corsair one year ago. )
These ( The first one ) and these ( 3rd from the bottom ) are performing close to the Mushkin, and more price friendly.

PS. I was a little incorrect about the CH-5's, 'cannot run at low timings'. Its the RAS to CAS that is lower on the BH-5's, but that is the most significant factor of memory speed for a Intel rig.

 

[Joe DeFuria]

Thanks again AAlcHemY,

Seems like you picked middle of the road in price / performance, which typically is always better bang-for-buck range. Looks like the Mushkin is about as "top of the line" as you can get in terms of PC 3500 ram. So now it's just a question of whether to go for that, or "1 step down" and save $50.

BTW...can you recommend a site / page the explains what all the timings mean? You mentioned RAS to CAS is the most important figure for Intel systems...I don't even know which (2.5-3-3 for the OCZ Ram you linked to) number that is. (Though I'm guessing the first number.)

EDIT: I was wrong...For those as clueless as me, the numbers are:

CASS Latency-RAS to CAS- Precharge Delay- Active to Precharge Delay

If I were to go and actually buy today...I'd probably go with the Kingston ram (PC 3500, 2-3-3-7) that you linked to...only about $10 more than the 2.5-3-3-7 OCZs, but $40 cheaper than the 2-2-2-6 Mushkin...

I also just found out from Mushkin's site that they only guarantee 2-3-2-6 for Intel chipsets...

 

[AAlcHemY]

Thanks again AAlcHemY

No problem, glad i can help.

Seems like you picked middle of the road in price / performance, which typically is always better bang-for-buck range. Looks like the Mushkin is about as "top of the line" as you can get in terms of PC 3500 ram. So now it's just a question of whether to go for that, or "1 step down" and save $50.

Its up to you if that extra 5/10Mhz is worth $50.

BTW...can you recommend a site / page the explains what all the timings mean? You mentioned RAS to CAS is the most important figure for Intel systems...I don't even know which (2.5-3-3 for the OCZ Ram you linked to) number that is. (Though I'm guessing the first number.)

I found this a very good explanation.

And its the second number normally.

 

[Joe DeFuria]

And its the second number normally.

Yeah...I just found that out...thanks!

 

[Tahir2]

http://www.pcstats.com/articleview.cfm?articleID=873

Joe I believe this article will be good background information in real world tests on latency vs bandwidth on a P4 DDR 400+ machine!

 

[Joe DeFuria]

Thanks!

 

[chavvdarrr]

If you're going to overclock, perhaps 2.4/2.6C is best-choice CPU. With good overclocker-friendly MB its limit will be @ 3.2/3.4 (same as for 3.0). And the pleasure of making 30% overclock is much bigger than making 10% ...
In both cases you're max OC won't be FSB limited, but with lower multiplier you'll end with higher FSB per same clock (say , 500 vs 440). And with the difference in CPU price you cover the difference in memory price... of course that's only if you DO want to make maximum OC...
What MB you look for?