So my MBP was in the shop for an ODD replacement under AppleCare. So I took out my (upgraded) HDD and 8GB RAM (though it was 1067mhz, not 1333 because it came from my MBP that Apple replaced) and put the stock back in. I put the RAM in my mom's unibody poly MacBook so I could share it with her for the time being without having to put up with it's 2gb RAM slowness. She thought it was amazing and super fast, so she wanted to keep the ram for herself. So I thought "if she wants it, maybe she'll let me upgrade mine!" She did not let me upgrade mine. Instead, she let me get one 8GB 1333mhz stick so I could upgrade to 16GB in the future. tl;dr: Is it okay to run just one stick of RAM?