Shoutbox

Also note that many current hard disks have a feature called S.M.A.R.T.. This means the hard disk can report back some variables back to the motherboard (or any program which calls upon these funtcions). Temperature is one of the standard variables which can be reported (without the need for an external sensor).

50°C is indeed not a (too) high tempurature for a modern hard disk.
Though it depends from disc to disc. The normal, average, optimum and max temperatures for a hard disk can be found in the manual or specs of the hard disk.

But it is indeed true that a much too high temperature will shorten your hard disk's life compared to an optimal temperature.

Although, it must be said and noted that a constant temperature, even if it is high!, (because of constant running), is far and far better than a temperature which changes all the time from room temp to high (or even only optimum) tempn, and back (because you only use your PC a few hours at the time).

The thing which shortens the lifetime of any hardware component (and this goes for any hardware, thus also for non-computer related equipment also like video players, dishwashers, radio, whatever) is not so much running at high temperatures (or humidity for that matter) but the changing in temperatures.

This is because materials expand or contract due to temperatures (or moisture gets condensed due to changing of humidity, etc). And it is this expanding/extracting, aka changing of environment, which damages components more than anything else...