Actually mindleak and Holliday are closer to the truth, Doc. MTBF (Mean Time Before Failure) on a hard drive is 100,000 hrs so spinning mechanical failure is minimal. As you say the head is suspended from the spinning disk by the cushion of air from the spinning disk. This doesn't exist when the hard drive isn't on and thus is more susceptable to shock damage,
especially if you do not shutdown your OS properly .
Capacitors in the power supply can handle the inrush, yes. But this is different from a turn on condition where the caps go from nothing to full capacity and this is EVERYWHERE there is voltage applied to a discharged capacitor. This quick, full range charge is what minutely stresses the caps. Caps in switching power supplies operate over a fraction (<20%) of their full capacity time when working normally (up to full load). Other caps for surge supression DO operate to full design voltage and/or charge ranges but then surges are not a normal occurance, only in bad power sources and
during turn on .
Doc has an excellent point for cooling though. Since most fans don't have dust filters it becomes important to clean whatever they are blowing on, especially a heatsink. Over time as the heatsink fins get more clogged with dust your CPU runs hotter. As a rule of thumb I never run a CPU over 60C, otherwise I buy a bigger heatsink. Also as Doc mentioned lots of fans help, I have seven fans in my main system so lots of air is moving around (no it's not that loud, that's why I have lots of small, quiet fans). If you run your 'puter continuously with unfiltered fans, regular maintenance is a must.
I'm sure y'all will let me know if I was wrong about something.
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{RN}Earendil
SysAdmin of Boston Freelancer server {RN}