Coil whine is a high pitched sorta whistling noise than can be produced by electronics, particularly electromagnetic coils when current is passed through them.
This phenomenon is particularly common on graphics cards and power supplies, and often more noticeable as they are found in otherwise quiet environments, but any component with electromagnetic coils can be affected.
So is coil whine normal? Yes, but in rare cases it can be a sign of a problem, such as a poorly connected cable or a badly worn electromagnetic coils (which could occur after several years of use).
If you have any questions or concerns about your CORSAIR power supply's coil whistling, please create a ticket with our support team.