First of all, look at the 350W power supply you originally used when it was working fine. Later on, the power supply was replaced by a 330W power supply. So far we have decided that the power supply is definitely a problem. At least there is a problem of insufficient power supply. Because the optical drive these devices only work when the power consumption. Secondly, because the power supply is always in a situation of insufficient power supply. The hard disk appears to sound wildly loud, and the speed and slow, it is recommended to use HDD test hard disk, there may be hard disk house bad sectors. Because the power supply causes the hard disk to work under low voltage for a long time. The motor may be damaged. Finally, you said the USB power supply problem, the standard power supply of USB is 500 mA. Generally there is no problem. Mainly caused by many mobile hard disk itself on the power supply control. You can add a mobile hard disk external power supply to try. So the final conclusion: First, it is recommended to replace the power supply. Second, it is recommended to detect whether the hard disk has bad channels need to be replaced.