2DIMMS vs 4DIMMS, Which RAM configuration is best?

I've never really understood the nitty gritty details on selecting the right combination of RAM, but as I'm considering an Alienware M17Xr3 for my next purchase, I'm honestly stuck in what I should choose.

First of all, how many DIMMS? 2 or 4? Is there a noticeable difference in performance between say, 2x4gb and 4x2gb? (Assuming 8GB is the max amount of RAM I would want to have, no upgrading in the future)

Also, for the new i7-2720qm processor, is there a "sweet spot" for the amount of RAM (6GB vs 8GB)? Currently, on the Dell site, they're offering 6GB (2DIMMS, meaning 2GB stick + 4GB stick) as default, and 8GB (4DIMMS, meaning 2GB each stick). Are there any rules in choosing RAM where "even" number configurations are better than "odd" number configurations?

Any help would be appreciated

 

Just go with the basic 4gb ram. Then buy some kingston hyperx 1600 ram (and the 2720qm). 16gb of that ram is just 200 bucks on newegg or amazon. That would get you maybe 8gb on the dell website? dell overcharges a lot

 

Is it easy to access the RAM slots on the M17Xr3? If so, I think that's what I'll do.

 

The two back slots are easy to acess. The ones under the keyboard are more difficult. Look on youtube for m17x r3 ram swap or something like that, one of the guys here made a video of how to switch out all 4 DIMMS

 

Here you go:

YouTube - joebarchuck's Channel

 

Thanks for the advice guys!

Also, when purchasing memory, is there a difference between Desktop and Notebook RAM? I'm under the impression that DIMMS refers to Desktop, and SODIMMS refer to notebook? The kingston hyperx one you suggested seems like it's meant for Desktops. Would that be a problem for the M17X?

Here's one that I'm thinking about getting:

Newegg.com - G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Desktop Memory Model F3-10666CL7D-8GBXH

 

That's desktop memory.

There is laptop hyperX.

I disagree with the people suggesting you get such expensive RAM. Are you using this rig for gaming? If so, 8GB is very much enough. All you really need is another 4GB and you can easily add that to the 4GB that comes with your system for $40.

Newegg.com - G.SKILL 4GB (2 x 2GB) 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10666) Dual Channel Kit Laptop Memory Model F3-10666CL9D-4GBSQ

Seriously, that 1600 speed RAM is twice the price and the only difference you would ever notice in speed is during benchmarks.

 

That is true, but taking apart the laptop to get to the RAM underneath the keyboard is not for the faint of heart. Joebarchuck's video makes it look simple enough, but it aint for me! If you don't mind doing it, your advice is solid. Keep in mind if you ever have to exchange the laptop, you will have to tear it down to get your RAM back out.
I am replacing my stock 4GB with 2 4GB sticks (8GB total) in the back slots. The HyperX 1600 MHz is only about 20 bucks more than the 1333 MHz 8GB memory kit. Since I have spent over 2K on the laptop already, what's 20 bucks? Plus, if I ever have to exchange the laptop, the swap out back to the factory RAM will be much easier.

Here is a link to newegg. They are out of stock, but this will give you the part number:
http://www.newegg.com/Product/Produ...=skim525X832Xe07aa92f035c5071e7ec1f527195cd23

 

As a note, you MUST get DDR3 SODIMM. SODIMM and DIMM have totally different pinouts/layouts, and you are correct to think that SODIMM is for laptops only, and DIMM is for desktops only.