Originally Posted by NitroPye

(Disclaimer: This is an over simplification of a complex topic)[/i] Machines crash when a program tries to write to RAM that isn't there typically. If you've maxed out the available RAM on your machine any modern o/s will properly handle swap (as in use your disk as RAM for non active applications). The only times when running your machine with the RAM full (which my machine is typically at 90% used when working) are when the O/S incorrectly handles the swapping and tries to write to non existent RAM which usually just will result in the program crashing. Now if it accidentally writes over RAM in use, more specifically where the kernel resides you will get a full system crash. This has little to do with running with minimal free RAM and almost all to do with the operating system making a mistake.