Storage Solutions Portable HDD -- Strange problem experience

[Scarecrow]

Ok, got my first portable HDD(Buffao 320GB) 2-3 days back. Was Happy:clap:. But when I connected, it did not recognize itself and to my surprise kept on showing "New Hardware found" and asking for drivers. Tried like many time on each available usb port and sometimes even my PC was not able to detect it.

Then tried it on my bro's laptop, voila, it got connected and was working perfectly.

Then once again tried it on my PC still the same problem occurred. So did a troubleshooting for usb devices, during this there was a point mentioned that if the usb device does not get the required power it fails to get connected. So exchanged my old mercury 400w PSU with CM 600W PSU, and the HDD got detected and working perfectly till now.:hap2:
Can somebody explain me as to how my old psu could not deliver the +5vdc on USB ports yet the computer was fully functioning.:S

Have noticed one more problem, whenever i try to safely remove the HDD 1st attempt it always denies but 2nd attempt it gets safely removed. Experienced this every time I want to remove it.:huh:

 

[nRiTeCh]

are you connecting it via your cabinets front panel usb??
connect using rear side motherboards usb.

laptops have similar powered usb as they are,unlike desktops front panel ones--low powered.

 

[Scarecrow]

actually when i changed my PSU(to CM 600W), HDD was detected and running perfectly on all usb ports(front and back). but with the old psu, hdd was not detected on any of the usb ports(back as well as front)

 

[nRiTeCh]

what sense does it make u to try old psu on the hand you are having a good CM 600W??
dont use the old ones some day it may kill your dear machine.