How long do you need to hold down the power button to turn off a PC?

According to Raymond Chen from Windows development, holding a PC's power button for 8 seconds triggers the kernel to create a dump file for error reporting, while 12 seconds forces a complete hardware shutdown without OS notification. However, most motherboards appear to implement force-power-off in 4-5 seconds instead, suggesting manufacturers deviate from ATX specifications, and the timing varies depending on individual motherboard designs.