Anandtech has some fantastic articles on memory speeds and the impact on applications, such as http://www.anandtech.com/show/7495/adata-xpg-v2-review-2400-c11/6

Anandtech has some fantastic articles on memory speeds and the impact on applications, such as http://www.anandtech.com/show/7495/adata-xpg-v2-review-2400-c11/6 http://www.anandtech.com/show/7495/adata-xpg-v2-review-2400-.... There are measurable differences, though they are "slightly pushing the edges" rather than being make or break.