How do you stability test your systems?

For new builds I test for 24 hours with

Memtest86
Prime95 (priority 10 large FFTs)
Sandra's Burn in Wizzard (memory and CPU)
3dMark 2005 on a continuous loop.

(Alternate method)
Sometims I run Sandra Burn in with only CD-ROM tests, 3d Mark and an extended hard drive test all at once. Maybe even run HD Tach on the 2nd hard drive while all this is going on. Or maybe defrag all the hard drives if its a new build (since I would done a full OS backup to a network drive prior to stress testing)

My thinking is that this puts a lot of strain on the PSU.

When I overclock I usually do the same, but for no more than six hours. I usually only overclock when my system is getting too old for new games, I have money for a new system and there is new generation of motherboards/CPUs I haven't built yet.

Anyway thats how I prove to myself that a system is rock solid.

Whats are your methods?