Upgrade RAM: Two, 2GB memory cards or will one 4GB memory card work?

If this is the right page for your model, you can have mismatched RAM:

http://eshop.macsales.com/shop/memory/Apple_MacBook_MacBook_Pro/Upgrade/DDR3

So 4GB in one slot, the other empty or with 2 GB in it for 6 total...

cmhall9 said:

I want to upgrade from 2GB to 4GB. Do I need two 2GB memory cards or will one 4GB memory card work just fine with the other slot empty?

I have a MacBook Pro 13-inch, Mid 2009
Processor 2.26 GHz Intel Core 2 Duo
Memory 2 GB 1067 MHz DDR3

Click to expand...

RAM works best in matched pairs as it allows it to run in dual channel.

For best performance I'd recommend getting 2x2.

do not worry about pairs , performance advantage is very minimal.

1 stick will do fine.

I wonder if there is a gain in battery life by running just one ram stick instead of two when the total RAM available is equal in both cases.

If it says the Mac's maximum RAM is 4gb, does that mean 4gb per stick or 4gb total? Could I run 8gb total on my Mac? I have a Mid-2007 Macbook.

seanirish said:

If it says the Mac's maximum RAM is 4gb, does that mean 4gb per stick or 4gb total? Could I run 8gb total on my Mac? I have a Mid-2007 Macbook.

Click to expand...

The Mid 2007 MacBook (MacBook2,1) is limited to 2GB per slot, but will not use more than 3GB total. - So, you can install 2 x 2GB for a (slight) speed advantage with a matched pair, but only 3GB maximum will be recognized.

I have 2x2 right now and it recognizes that it has 4GB of RAM in it.

Then, you don't have a mid-2007 MacBook, but you have a late-2007.
The model identifier in your System Profiler will show that you have a MacBook3,1 - which also will work with up to 6GB RAM, and will, in fact, work with a single 4GB stick, if that's what you want to install.