Computer startup sound, after a while on the good, how?

1, the computer power supply or CPU fan aging, fan bearing lubricant solidification, fan rotation friction caused by the noise; after a while, the lubricant is softened by heat and can continue to protect the bearings, the friction is reduced, the noise disappeared; it is recommended that you replace the fan or disassemble the fan into a few drops of lubricant.

2, just boot system startup, CPU load, in order to ensure that the CPU does not overheat, the CPU fan is also running at full speed, thus generating noise; into the system after the CPU stabilized, the noise disappears. This is a normal phenomenon and does not need to be dealt with.