Macbook Pro Order of RAM Loading This may be a silly question because I'm not fully sure how RAM works and is loaded, however I'm trying to figure out a potential configuration here.

I have two RAM sticks that are both spec matched for my MBP. One of them is a 8gb gskill  stick, and the other is a 4gb Samsung stick. I rarely use more than 8gb of RAM, however it does happen on occasion.

I would think that it would be best for me to fill the entire 8GB stick first, and then load data onto the 4GB stick if the 8 overflows. This said, I'm not sure if it's possible to load the sticks "one and then the other" like this, or if it would be beneficial.

Is the order that info is loaded into RAM determined by the slot that the stick is in? If so, which slot (top or bottom) should I stick my 8GB stick into in order to make sure that it's used before the 4gb stick?
Typically you want to install memory in pairs (i.e. two 8 GB "sticks" or 4 GB "sticks") to make use of something called the dual-channel memory interface. What that in essence means from your perspective is that the computer can use two memory modules at once, one in each "channel," if they are matched. That gives better performance than using one and then the other.

The way Mac OS X works, your computer will use all of the available RAM when it can to cache things that it might need later--even if you don't need them in RAM right at the moment. The price of RAM what it is today, I would try to order another module of the exact same type as your 8 GB.

Source: http://support.apple.com/kb/TA38415?viewlocale=en_US&amp;locale=en_US