How does the CPU sound like a generator?

Q: A boot CPU like a generator is very loud, and then the main version of the interface after the hint: CPU fan errow! Press F1 to enter the next step, but will appear to prompt you in Safe mode, the last normal configuration or the normal start of the interface, and then choose a can sometimes go in, sometimes can not go in, but anyway the CPU still very loud, this how?

A: There is a possibility that there is a problem with the CPU fan! BIOS post includes detection of fan is normal, once the fan is damaged, the system will start protection to prevent burnout of the CPU, self-test will not pass, show fan error will automatically shutdown.
Workaround:
1. Replace the fan (90% probability)
2. Only the motherboard is left. (generally very few)