Hi. Every red peak that you can see on the picture, the HD makes the tipycal HD scratch noise. It happens sometimes, every 30 seconds, or more and sometimes without doing anything more than writing or surfing with Safari. The red peak means that HD is writing something. I have to say that a bit down about hardware problems, but concerning OS, it's better than I expected. It's awesome. It took me more than a month to make my decision between Windows or Mac OS, but I have made the correct choice.