Installing Memory and Apple Warranty

Removing the memory installed by Apple does not void the warranty......assuming you don't accidentally damage the computer in the process. The replacement memory you installed wont be covered by Apples' warranty of course.

A lot of people think it's a good idea to hold onto the original RAM stick. Applecare techs are often quick to make the assumption that replacement RAM might be faulty if something goes wrong with your computer, so having the original RAM to reinstall can help speed along the diagonstic process

 

First of all, make sure to test run your system "AS SHIPPED" just to make sure everything is working properly.

"DUAL CHANNEL vs QUAD CHANNEL
In order to get the full benefit of the Mac Pro's 256 bit memory data path, you'll want to populate both memory riser cards, each with at least one matched pair. If you put your memory on only one riser, you are dropping from quad channel to dual channel mode. "
BareFeats has a great article explaining it all.
http://www.barefeats.com/quad09.html