Systems that reboot sporadically, experience Blue Screens of Death (BSoD) and other strange system behavior can often be attributed to bad memory. Below are some RAM testing recommendations. If either program identifies bad memory, try reseating the RAM as this will often fix problems. If it doesn't alleviate the problem, try to narrow down the bad stick(s) by installing one stick at a time and running the memory test.
If you can boot to Windows
There is a commercial testing application from http//www.passmark.com called BurnIn Test. The trial operates for 30 days and is very good at detecting bad RAM within minutes. We find this program to be more reliable at detecting bad RAM than the method listed below.
If you cannot boot to Windows
There a free RAM tester available at http://www.memtest.org. Download the ISO, burn it to a CD, boot the sytem from the CD. Let the application run for a few hours or overnight.
Note: If you are having problems with BSoD's while Windows is loading, please see the Blue Screen When Windows 7 Loads article.