memtest86
http://www.memtest86.com/
memtest86+
http://www.memtest.org/
memtest86 3.5は再起動してしまう問題がある。
http://en.wikipedia.org/wiki/Memtest86
The 3.5 version is known to fail on some (or many, or most) computers with 4 gb of installed memory (the failure results in a spontaneous system reboot soon after the program starts running).
