cpu overheating

[Alan]

This might be useful in terms of test tools. Cluster people care a lot
about getting their systems reliable (if you had 512 PC's you would too)
and there is some good info in that posting about stress tools including
va-ctcs/cerberus and the like. 

http://www.beowulf.org/archive/2006-October/016669.html

For I/O stressing take a look at

http://samba.org/ftp/tridge/dbench/

and the related tbench tool for network stress.