Not recognizing external HD...problem with USB ports

No, I'm not using Migration Assistant.

All of the drives I tried using are currently formatted NTFS which Mac's can read but not write to which is fine because I'm only transferring data to my Mac from my old PC. The only drive that my iMac recognized is the external drive that is powered by a USB adapter, and only in USB ports 3 and 4, not 1 and 2. The other USB powered external drives I tried were not recognized at all in any USB ports.

So, I have a few updates to this problem.

I just got my new Macbook Pro (non Retina) today in addition to the iMac I got last week, and it also has the same problem of not recognizing or mounting either of my bus powered external Hard drives.

I spoke to several people when I called Apple Care and nobody was able to help me or explain what the problem could be, so I'm returning my iMac for an exhange.

On a hunch I decided to call the manufacturer of my ioSafe Rugged Portable, and they were more helpful than Apple. They stated right away that Apple uses a high/low power setting for their USB ports, and because of their proprietary USB technology, certain third party devices such as external hard drives are not provided enough power for them to run properly. Of course when I told the Apple Care Senior Advisor that I was speaking to this information, he rudely flat out denied that this was the case.

I'm a mobile DJ and I rely heavily on external hard drives for my huge music library, so I'm ripping my hair out right now. For an iMac, and Macbook Pro that I paid almost $3,000 EACH for, they should absolutely be able to handle such a simple task as being able to power and mount an external hard drive.

Thank you! Yes, I did end up getting the new USB cable from ioSafe, and now it works perfectly which was a huge relief.