Rookie question about external hard drive!

If it comes with a power supply that will be required for the drive to function at all. It doesn't harm the drive.

 

USB ports are not all alike. Older ones output less power to peripheral devices - enough to power a mouse or keyboard, but not enough to power a spinning hard drive or DVD burner. For this reason those peripherals often come with an additional USB cable which is used solely for power, and isn't necessary on most current computers which output more power to each USB port.

If it works with one cable, then you don't need the other.

 

So it sounds like it comes with both a Type A plug (the larger rectangular one) and a Mini-B plug (the smaller, thinner one).

Both should support providing 5V DC at up to 500mA, but it sounds like the Mini plug might not be doing so and therefore the drive is not receiving enough power to operate normally.

Since the Type A plug is providing sufficient power to allow the HDD to operate, you can just use it and ignore the Mini-B.

 

As already mention the thick one is USB + power
if the drive didnt power up with just the thick one plugged in means you need more power which the thin one is for power only. Hence your drive didnt get recognised

 

Jesus, why can no one provide the right answer?

Friend, in order for your hdd to work properlly, you have to connect BOTH ends of the cable to the computer, thats how this specific model you got works. Period. I happen to have a similar drive, in my case, a Trasncend drive.

Now, you may need extra usb ports in order to do that. So get a macally 7-port USB hub, they have in grey to match the macbook (and white too)

 

You're the only one that gave the wrong answer! I too have an external drive with two USB leads, and the instructions quite clearly say that only one is required if you have enough USB bus power. This is borne out by the experience of myself and many others.

 

Actually, the quote below is correct, and was posted before you.

In the case of most current Macs, yes. In the case of some older computers (Mac or otherwise) there may not be enough power from only one port (USB 1 and USB 2 were .5A power output per device/plug IIRC). FWIW, it won't hurt to plug both in even if only one is enough. That said, I had an IDE-USB adapter with the double plug like this (for a 2.5" drive) and don't recall NEEDING the second plug often, but after a few failed attempts with just the main plug I ended up just using both.

 

That would be correct for this type of cable:



Where both the black and red large plugs would connect to the Mac and the small black plug would connect to the HDD.

However, from how the OP is describing their cable, it sounds like what they have is a large and small plug on one end (either of which can be plugged into the HDD), and a large plug on the other end (which plugs into the Mac).

 

In the cable above, the large black plug provides both data and power and the large red plug provides additional power. So it would certainly not hurt to keep both the black and red plug connected to USB ports as that way if the drive needs more power, it has access to it.