An answer which is lacking, but still current is this: A computer when forced shutdown (as in 'removed power cord or alike') can DAMAGE the electronics. (this does not apply to the power switch as it does a 'safe' power cycle that does not harm the electronics, just not that good for a stable HDD state, or and can cause data loss as already answered above).

The sudden surge of power that can occur when the power is removed forcefully (think 'spike') can in rare instances exceed the filter limits / ICs breakdown voltage. If this happens inside CMOS or other Memory it can permanently damage the 'cell' or corrupt data on the 'cell'. It is these days a rare thing and most systems have countermeasures for it (that can fail).

This situation is especially true if motors are used (like for a Disk Drive). Since the spin-down can sometimes cause a spike on one of its lines (+12,+5,-5,0). This does not have to be the power lines of the motor itself (due to 'ghosting').

Signals lower than 5 volts rarely do this as most IC's are designed to operate with 5 volt signals, although there are processors that utilise 3.3V as its max voltage most often there still shielded the same as the 5 V.

An answer which is lacking, but still current is this: A computer when forced shutdown (as in 'removed power cord or alike') can DAMAGE the electronics. (this does not apply to the power switch as it does a 'safe' power cycle that does not harm the electronics, just not that good for a stable HDD state, or and can cause data loss as already answered above).

The sudden surge of power that can occur when the power is removed forcefully (think 'spike') can in rare instances exceed the filter limits / ICs breakdown voltage. If this happens inside CMOS or other Memory it can permanently damage the 'cell' or corrupt data on the 'cell'. It is these days a rare thing and most systems have countermeasures for it (that can fail).

This situation is especially true if motors are used (like for a Disk Drive). Since the spin-down can sometimes cause a spike on one of its lines (+12,+5,-5,0). This does not have to be the power lines of the motor itself (due to 'ghosting').

Signals lower than 5 volts rarely do this as most IC's are designed to operate with 5 volt signals, although there are processors that utilize 3.3V as its max voltage most often there still shielded the same as the 5 V.

@samuel, Yes I am. but the operational voltage indicate what sort of inductive spike you can 'expect' (either the isolators /protaction for it, or the amount of it)