A specification for reporting of hardware errors e.g. from the chipset, to the operating system.

It is typically used to signal attention for non-recoverable hardware errors.

In the event of a fatal hardware error, they give these beeps:

A hardware error on the other hand happens in a more or less random way.

If a hardware error causes its state to change in an unexpected way.

Writers went so far as to exploit known hardware errors to produce effects that the manufacturer of the computer had not intended.

In the event of a hardware error, the vmkernel can 'catch' a Machine Check Exception.

Processor state is buffered in a way that allows precise core retry for almost all hardware errors.

Making reliable distributed systems in the presence of hardware errors (thesis, pdf, long)

Industry executives and technical experts said they were less concerned about the actual hardware error than by the way Intel was responding.