Physical memory quantity vs. performance

Sometimes motheboards won't support X number of sticks at full speed, and have to slow them down. To use dual channel memory you'll need 2 sticks (or 4 sticks, or sometimes even 3 sticks will work depending on the chipset/motherboard) Beyond that, that's really no advantage or disadvantage to it, except that if you use 4 sticks and fill up all your slots you can't upgrade without removing some of those sticks.

While it depends on a few differing things, such as processor type (AMD/Intel) as well as motherboard manufacturer and ram, two sticks of ram will run better than 4 sticks, the reason being, command rate, that is 1T or 2T.

I wish I could find the article i was looking for, but this will suffice somewhat.
http://www.anandtech.com/memory/showdoc.aspx?i=2560&p=2

In the article they compare 2x512mb to 4x512mb sticks and its pretty neat, though again, not the article I had read initially, though if I find it I'll edit it in.

EDIT: Heres another comparison, while its not directly related per say, it does touch on the topic and issues with 4dimms vs 2dimms
http://www.xbitlabs.com/articles/memory/display/2gb-ram...

I forgot to mention the assumption that the timings were the same as well.

Thanks for the links. I'll take a look.