I tried searching up this question but could not find any results. I was watching the youtube video on the ram upgrading and I noticed that the person took out 2x 1GB ram pieces and put in 2x 2GB ram pieces. The ram I purchased is 1x 4GB piece and I am just wondering if there would be any drawbacks for using 1x 1GB and 1x 4GB in my set-up. I remember that for PC, it's best if the RAM is the same size/speed/manufacturer. My newly purchased ram is from OWC. Additionally, if I decide to only have 1x 4GB left in there, does it matter which slot I put it in? There are two slots that are empty and I'm not sure if there is a primary slot or secondary slot. Thanks.