RAM Question

[Redundant]

Is there any advantage/disadvantage to having 1 GB (2 x 512 MB) compared to 1 GB (1 x 1 GB) besides having an extra RAM slot? Does the "Dual Channel" feature in a set of two make it faster?

Also, why is the Latency of DDR2 so much higher than that of DDR1?

[.Maleficus.]

Yes, I believe dual-channel is better.

No idea why timings are different between DDR and DDR2 though.

[progbuddy]

Dual channel has, obviously, twice the number of contacts. This speeds up loading/unloading time of RAM.

[Redundant]

Ok, so now that I know that Dual-channel is faster, is lower latency more important or higher speed? Here are the two I'm comparing:

http://www.newegg.com/Product/ProductCompare.asp?SubCategory=542&CompareItemList=N82E16820145539%2CN82E16820145566

What do they mean by SLI memory?

[dgrmkrp]

think of this.. what is the speed? why is it measured in mhz?.. we must look at the hz part.. 1 hz is one cycle/second... lots of this cycles naturally take place in a ram module, but before these can be considered data transfers, the memory controller sends querys and bla bla.. i don't know too much.. but these commands take cycles and that's what they mean by latencies: how fast does your memory respond.. when latencies add up, it sometimes is better to have tight latencies vs "speed"... given the same frequency, of course better latencies are better.. but in some cases (ddr400 2-2-2-5 vs old ddr2 no-name memory at 533mhz), latencies make a huge difference even between different models with different speeds..
dual channel offers higher bandwidth(2x)... that's why we think dual channel faster :)plus, the memory controller works in a more efficient way.. and the entire memory-subsytem is better than nondualchannel :)

[CanaBalistic]

Well... 2 sticks of ram wont give you dual channel. You need 4 sticks for dual channel to work.

[DaveW]

Yes it will. You can run 2 sticks in Dual channel, or 3 sticks with 2 in dual channel, or 4 sticks with matched 2 in dual channel...etc.

All you need is the exact same RAM.

-Dave

[Cevinzol]

Read the articles listed in this page
http://www.tomshardware.com/motherboard/index.html
specificaly:
beginners_guide_to_motherboard_selection (http://www.tomshardware.com/2006/07/26/beginners_guide_to_motherboard_selection/)
tight_timings_vs_high_clock_frequencies (http://www.tomshardware.com/2006/03/31/tight_timings_vs_high_clock_frequencies/)
navigating_the_memory_upgrade_jungle (http://www.tomshardware.com/2006/03/24/navigating_the_memory_upgrade_jungle/)
and
how_much_ram_do_you_really_need (http://www.tomshardware.com/2005/12/13/how_much_ram_do_you_really_need/)
though the last one is a little old

'n joy

[MitaPi]

Just to throw this in here... I might be wrong so someone correct me if I am. I think slug toy actually told me this a little while ago...

Having, lets say "DDR2 1000" with "cas latency 4" would be better than having "DDR2 677" with "cas latency 3". The higher clock speeds make up for the higher latency. You want high clock speeds (DDR2 1000) with low cas latency when you are looking at ram modules.

... I think. lol sorry slug, I think I was spacing out when you explained it to me ^_^

Some good memory I recently looked at were the Mushkin Redline series. You can buy them as 512's or as 1GB's. I personally would go with the four 512's for costs sake. But if you want the super good stuff and you have the money to buy it. Then go for the 1GB version.

...Which is around $450 for two 1GB modules. Saves you two spots and gives you 2GB's. Pretty sweet. But also very pricey. :(

Happy Modding,

EDIT:
I personally would go with the DDR2 675 version of those corsair's you listed. But that might be just me.

[Redundant]

After reading the "Tight Timings vs High Clock Frequencies", it appears there is not much of a difference but I did not understand a majority of the article...

MitaPi, why would you prefer the DDR2 675? Does it have something to do with the SLI Ready label in the picture?

[CanaBalistic]

Humm, thats odd. My text book says nothing about dual channel memory. However it does say that RDRAM can be used in dual channel mode without matched pairs. Apparently RDRAM was designed for this. So logicly, it could be the same for DDR.

I stand corrected.

[MitaPi]

After reading the "Tight Timings vs High Clock Frequencies", it appears there is not much of a difference but I did not understand a majority of the article...

MitaPi, why would you prefer the DDR2 675? Does it have something to do with the SLI Ready label in the picture?


Dont pay attention to the SLI lable. That just means that someone that was certified to do so had tested that memory in an SLI setup. Which is dual GPU in case you didnt know.

EDITED
Read Slug Toys Post, It's mucha betta ^_^

[Slug Toy]

ok the tight timings and high frequency thing can be explained using some simple math.

first keep in mind that the higher the frequency, the higher the bandwidth no matter what. the tighter the timings, the higher the bandwidth because the wait time between signal transfer is lower.

now lets look at some theoretical modules. lets take good old ddr400 ram with 2-2-2-5 timings, and ddr800 ram with the common 5-5-5-12 timings.

division will answer your questions in this case. you just divide the timing by the frequency. for example... in the ddr400 module, the cas timing of 2 divided by 400 MHz will give a value of .005. this correlates to a certain amount of time. i think i worked it out to the value being a portion of a millisecond, but that was a while ago. so that means .005 milliseconds, or 5 nanoseconds. and thats not unreasonable seeming as the recent x1950 uses .91 nanosecond ddr4.

anyways... 2 divided by 400 gives .005. how about the cas timing of 5 divided by 800 in the ddr2? that gives a value of .00625. this is a larger number, meaning an overall larger latency... which is bad. so in this case the theoretical ddr400 module wins.

what about the last timing there? 5 versus 12... lets see. 5 divided by 400 gives .0125, and 12 divided by 800 gives .015. ddr400 still wins.

in this case, the latency war is won by ddr400, but ddr800 still will give better bandwidth and performance. the frequency is the largest factor, and timings just improve upon this.

this is why i really like mushkin's recent ddr1000 modules that have a 4-5-4-11 timing. 2 divided by 400 versus 4 divided by 1000 gives .005 versus .004. 5 divided by 400 versus 11 divided by 1000 gives .0125 versus .011. in both cases, ddr1000 wins, and the 5 timing on the ddr1000 will match the corresponding 2 timing in ddr400. this is one of the few cases where ddr2 modules have won in latency and bandwidth at the same time.... and this is why i like those modules so much.

[MitaPi]

WELL YOU SCHOOLED ME! :eek: lol Well done Slug Toy... you mathematical bastard :D

You wouldnt be talking about the Mushkin Redline would you? Those things are HOT! ...in a good way! :p

[Redundant]

OK, so it took me a while, but I just understood what you wrote. :)
Thanks for the help on the timings thing.

[Redundant]

Now that I know how to find which timings/speed combo is better, I compared DDR2 675 with 4-4-4-12 and DDR2 800 with 5-5-5-12 timings. (Both sets are 2x1gb)

I came out with this:
For the DDR2 675 CL=4
4 divided by 675 = 0.0059... and 12 divided by 675 = 0.1777...
For the DDR2 800 CL=5
5 divided by 800 = 0.0062... and 12 divided by 800 = 0.015
So on the 675 the first 3 timings win and on the 800 the last timing wins
Would the 675 be faster?

Also, about that Mushkin RAM you liked, would it only be better is it was run at 1000 or would it still be better if the motherboard downgraded it to 800?
Sorry for all the questions. :D