Just a heads-up, I know that there are always topics about Apple computers and compatible RAM but I encountered something interesting and confusing. My Macbook was running fine but slow with only the default amount of RAM. I bought some third party ram for my Macbook that was branded adata. The ram ran fine when I put it in, passed all hardware tests including Apple's, and techtool pro's. But about every two weeks my volume would develop errors, this was seen in safari crashing, quicktime problems, apps failing to open. In the beginning the disk would pass the disk utility verify test but eventually it would report failure on exit. The problem went on for a couple of months, i would keep a whole disk image for backup every night as I didn't know how long the computer was going to last between crashes. Whenever I would reinstall I had to remove one stick of RAM otherwise the install woulf fail (I guess that forced it into single channel mode). This was my cue to try different ram, this time I bought some (cheaper) Samsung RAM. ALL my problems are gone, no glitches every app works perfectly all the time. I waited two weeks before posting as this is how long it would usually take for it to crash. I am reading all over the place about quicktime and safari crashes, for me third party RAM was the problem. I just wish there was an app that tested the memory better for compatibility.