Imac is not detecting my LaCie External Hard Drive

Check to make sure that the FireWire or USB cables are
correctly attached and firmly seated in both the drive and
computer's FireWire or USB ports. Disconnect them, wait 30
seconds, and reconnect them. If the drive is still not
recognized, restart your computer and try again. If they are
correctly connected and your drive still does not power on,
trying using the optional power sharing cable, described in
section 2.3 Connecting the Optional Power Supply of the LaCie Mobile Hard Drive User Manual.

the power circuit is most likely blown. You can buy an external hard drive case and put the hard drive in it. Be sure to buy correct size hard drive enclosure. The other way is to remove hard drive from external case and put into computer with a spare sata connection.

The funny clicking noise you are hearing is usually from a mechanical failure within the hard drive. The drive will need to be replaced at this point. If the drive is still under warranty you will want to process an RMA.

http://www.lacie.com/us/support/

Robert from Blitware

Hi,

The hard disk might have gone down . Kindly diagnose the disk and try . Good Luck

There should be a special USB wire that is available for portable hard drives. Basically it might just need power in which the The USB cable has two inputs so one is used for data transfer and the other for power.

Hi. Sometimes, there are compatibility issues on external drives. Most recent computers will read them while others may not. Either the external casing or the cable is causing this.

You're not missing any step at all, because with SATA hard drive if its really working your computer should
automatically detect it and since this hard drive suddenly stop working there's a possibility that its already
fried but if you want you can try this hard drive again to a different computer and if still not detected by
second computer its already dead.........

I am not really sure where to start here because I am a little confused about your setup here. It seems you made a great choice to keep Windows and your data on separate drives. Your primary hard drive is a really fast SATA Raptor drive, which is great, but I would never use an external hard drive for general everyday data storage. Many will probably disagree with what I have to say, but external hard drives should really be used only for temporary backup. I would never suggest using an external hard drive as your only copy of your data or for regular everyday use. There are several reasons for this:
1. External Hard drives are generally slower than Internal Drives.
2. Many of them come preformatted with Fat32, so you are limited to files no larger then 4gig.
3. They are more likely to fail because they are normally subjected to a greater likelihood of accidental bumping or dropping.
4. Many external drive enclosures are not properly cooled for continuous usage and thus lead to premature failure.
5. You often have no idea what brand of hard drive is actually inside the enclosure.

Don’t get me wrong, external hard drives are wonderful and I use them all the time. I have three LaCie 160 gig drives myself that I use all the time for temporary backup, but I rotate them so that I have 3 consecutive backups and would never use them (not just Lacie but any external drive) as my only backup or as a primary data drive. And yes, I have had to replace a few of them due to failure.

So to address your specific questions:

What went wrong? –
1. Bad Cable - Well it is probably unlikely, but I would first try another USB cable just to make sure the cable is not damaged.
2. Power Supply - Try another power supply if you have or can borrow one.
3. Controller Failed – The Controller inside the Lacie has failed.
4. Drive Failure – The Hard Disk inside the Lacie has failed. Drives typically have an average 5 year lifespan, some last longer and some can fail much sooner. Unfortunately, you rarely have any warning, thus the need for backups.

A power supply failure can cause this; I've just been through it myself. If you have access to another LaCie drive, try its power supply on the "failed" one and see if it works.