Hi,
Are you referiing to any particular hardware failure or you just want to generally check?
My suggestion is that a hardware failure will normally be very noticeable to you. Hardrive not working, no operating system but the computer will boot to BIOS and possible a little furhter but then freeze or reboot.
RAM being faulty will usually cause you some very loud beeping and no PC booting or boot to BIOS then freeze.
i could go on, do you have a particualr problem you are trying to diagnose?