不知道你的硬盤的u***** cable 插頭有幾個,some cable has 3 head, one for hard drive, another two for connecting to PC, you can plug both head to pc, so that the hard drive can get more power. some kind of u***** port in old pc does not supply much power. especialy when you plug a u***** 2 device to a u***** 1.1 port on a pc.