New answers tagged memory
Try uninstalling Adobe Flash. Flash doesn't work well on Macs. Flash games and Flash content in the Internet pages require a lot of processing power, which causes the CPU to go to the extremes and as a consequence heat builds up inside the Macbook. MacBooks (especially Air models) are known for poor inside ventilation.
I had the same weird behavior on a 17" Macbook Pro (Late 2011). So this is probably not a sign of trouble. I wanted to be sure that the memory was actually OK, and I remembered that there are two versions of memtest86: memtest86 (by PassMark, memtest86.com) and memtest86+ (GPL from memtest86.org) The Passmark versions seems to have more active development ...
The problem you are describing is a problem I had a while ago as well. For me the screen would get all messed up and depending on whether I was playing sound at that moment or not I would hear a loud screaming-like sound. Then after a couple of seconds the computer would reboot. Replacing the ram fixed it for me.
It is an infuriating problem. If your Macbook still doesn't work then you will need to take it in to an Apple Genius Bar to see if they can help you fix it (or arrange for a repair under warranty). Hopefully you have got enough data from your Mac so as to be able to back up, or continue working on a new Mac.
I also have the same needs but many such softwares are not free, thus I made one myself. Feedback is welcome. https://github.com/ningt/iStats
For OS X 10.11 or later, use this fork of MenuMeters: http://member.ipmu.jp/yuji.tachikawa/MenuMetersElCapitan/ (Open the .prefPane file by Ctrl clicking and selecting Open.)
This is the script of a similar bulk erase/copy routine I made with the help of klanomath in this related question - Find specific attached disk, not volume, by Applescript which you need to reference to see how the device name is extracted. I saved the script as an Automator Service, which I then tied to a non-trivial, in fact very hard to do by accident ...
How to upgrade RAM memory on MacBook White a1342 https://www.youtube.com/watch?v=xS6STfKdYFU
Top 50 recent answers are included