Can't Read External Hard Drive

securityhead88, a drive letter problem on one computer isn't going to cause an I/O error on multiple computers; the drive letter that a computer assigns it on one computer isn't going to affect what drive letter another computer gives it since Windows will just assign it the next available unused drive letter on that computer. At worst on a single computer it will get no drive letter but technically it doesn't even need one. HOWEVER it can't even get a drive letter if it isn't partitioned & formated which is where he has his problem. So using another computer to assign a drive is fruitless 1-because that won't apply to other computers, & 2-it isn't formatted. An I/O error on multiple computers is indicative of hardware errors or failure. The question is whether or not the failure is with the enclosure or the drive itself. In addition if the drive is sharing the same drive letter as another device (which is unlikely considering how they are assigned), assigning another drive letter can & would be done on that computer & not another one.

One thing to try would be to do a low level format, repartition, & then reformat.

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One thing I forgot to note is that different drives had different jumper positions for the master/slave settings that Dan Penny referred you to. You can usually tell the correct position from a little picure on the drive or you can google the model listed on the drive its self (not the model of the externel drive). You will find a position for master, one for slave, & one for cable select. Dan Penny suggested that you set it based on an optical drive if you need to put it temporarily in its place. I recommend that you do not choose cable select. If you put it on the same cable as your other hard drive you must use slave. If you put it on the cable that isn't connected to the main drive then you should chose master.

Do not touch the board on the bottom of the drive, do not stand on carpet, & ground yourself by first touching a metal surface on the inside of the case. Other wise you can cause static shock & possible fry something in the computer. It has happened to me.