RAM Question...

Your laptop will have 2x2Gb stick (that's how Apple ship them). It has 2 slots. If you want 8Gb you must buy 2x4Gb sticks and replace your existing RAM.

 

The 4 GB of memory that is installed is typically a pair of 2 GB DIMM modules (so that it will run in a dual channel configuration). Therefore, you'd need two 4 GB DIMM modules to upgrade to 8 GB of memory.

You can install an odd amount of memory (for example, 6 GB) by installing one 4 GB DIMM module and leaving an existing 2 GB DIMM module installed, however I wouldn't recommend it.

You can check to see if this applies to your MacBook Pro by clicking the Apple menu, click on About this Mac, and then click on the "More Info..." button. In the System Profiler window on the left hand side choose "Memory". It will then list the available slots and what is currently installed along with other details.

Hope that helps, have a great day.

 

You can put different sticks in your machine. In theory it will be slower if you don't match sticks though. In reality, some tests show a hugh performance gain and other show no difference. You probably won't notice a difference. More RAM is almost always better than matched pairs of less RAM. In your case, 6 GB (4GB and 2GB) of unmatched RAM will be better than 4 GB (2x2GB) of matched RAM. But 8 GB matched (2x4GB) will be even better.


I'm a fan of crucial.com and datamemorysystems.com.