I think this deserves a little more attention, as you aren't the only one who has experienced this 'phenomenon'.
See:
http://forum.xda-developers.com/showthread.php?t=429536
I have no clue what a 3-core cable is, but if we could find out what is actually going on here, it would be helpful.
I've experienced something along these lines in regards to a Toshiba external 2.5" hard drive that powers itself exclusively off of one usb port. Out of all of the usb cables I have that I know work on any other device, only two of them will power up this hard drive, regardless of what port it is connected to on my computer.