DDR3 dual channel vs tripple channel

[citan x]

I am getting the itch to get an Core I7, but need to make it easy on the wallet. If a get a 4Gb (2x2GB) dual channel kit, can I later get another 2 kits for 12 GB total and ran them in tripple channel mode?

 

[shempf]

sure. I plan on getting 2 kits of [2x2GB] myself. Same price as a 6GB [3x2GB] kit.

#'s show not much diff.

 

[exar333]

I checked Newegg, and a 2x2 DDR3 kit (rather cheap) was ~$90.00 while the 2x3 DDR3 kit was around $150.00.

There doesn't seem to be much of a price premium, and most of the 6GB kits are lower-voltage for the i7.

I also thought of getting a few sets of the 2x2 kits, but I think the 3x2 are better for an i7 build IMHO unless the difference from 6GB to 8GB will absolutely kill you.

 

[Denithor]

Read the AT i7 article for the portion on memory.

In a nutshell: if you run 3xDDR3 you get triple-channel. If you run 4xDDR3 you wind up with a funky hybrid of triple & single channel and memory performance measureably suffers.

In the four-slot configuration the first three slots correspond to the first three channels, the fourth slot is simply sharing one of the memory channels. The downside to this approach is that your memory bandwidth drops to single-channel performance as you start filling up your memory. For example, if you have 4 x 1GB sticks, the first 3GB of memory will be interleaved between the three memory channels and you'll get 25.6GB/s of bandwidth to data stored in the first 3GB. The final 1GB however won't be interleaved and you'll only get 8.5GB/s of bandwidth to it.

Before you make your decision, consider this: memory speed has almost no real impact on i7 system performance. Seriously. Going from DDR3-1066 to DDR3-1600 nets maybe a 1% advantage in real-world applications (video encoding, gaming, etc). So you will be better off buying 3x2GB of slower-clocked memory than 2x2GB of higher clocked sticks.

Here are some good kits:
G.Skill 3x2GB DDR3-1333 $145
A-data 3x2GB DDR3-1333 $145
Crucial 3x2GB DDR3-1066 $145

 

[shempf]

depends how one likes to justify things. 8GB (dual) cost me $160 versus 6GB (triple) $144. What I am planning makes $16 more for 2GB a no-brainer.

There is no end-all be all.

I haven't seen an numbers prove triple is remotely 'better' than dual [I also predicted this to be the case, so take that for what you wish]. I'd like to see some ("home")server based #'s and/or video processing, which I haven't yet.

 

[Denithor]

Dual channel vs triple channel on i7.

You're right, there's not much difference. Go for the 2x 2x2GB kits instead if you like and can find good pricing.

Like this:
G.Skill 2x2GB DDR3-1333 $80 shipped

 

[shempf]

I was just reading that article (think I've came across it before, looks familiar). Pretty much agrees with everything else I've read.

That's the memory I referred to above. Sounds like it can OC good too. You could also take out 1 stick to try triple-channel, for whatever reason.

& I have seen some articles post video processing (I forgot). Diff was moot there too, at least compared to using a C2D/Q6600 vs i7.