[QUOTE=kevinoxy;2153150]but I know there’s a way…[/QUOTE]
There is definately [B]NO[/B] way. A 3.5" HDD used 12V power and 5V power. The USB power is only 5V / 500mA (max if it was requested during USB enumeration).
By the way it is also holy crap to use 2.5" HDDs (doesn’t matter 5400RPM or 7200RPM) in USB buspowered mode.
you can use only 500mA current for buspowerered devices. And this is only possible if during USB enumeration the device requests 500mA. During enumeration only 100mA are alowed.
You can see the requested power consumption if you check your USB hubs in the control panel if I remember correctly. And I know there is NO USB powered 2.5" HDD that requests the power according to the USB specification.
What can happen using a USB powered 2.5" HDD:
[li]It may work.
[/li][li]You are lucky and your HDD does not work stable or does not work at all.
[/li][li]You are much more lucky and the power line of the used USB port or the USB port (or ports if you use Y cables) are damaged and can not used anymore.
The USB powered HDDs are more “dangerous” on Notebooks since it may happen that the USB buspower is a little weak and the powered device used therefore a little bit more current.
Unfortunately mose hardware vendors does not use fuses in the buspower line at all or only nonrenewable fuses that also makes the USB port not usable anymore.
At all I can not reommend 2.5" buspowered HDDs at all. If the HDD is build by yourself in an enclosure or you bought it right out the box… There is no guarantee it works or will not damage any components. Using a external power supply is the only real safe way.
You can also use FireWire with 6 pin plug. The buspower by the FireWire is much higher than the USB buspower (USB: 0.5A FireWire 1.5A)
All available 2.5" HDDs have during spinup a powerconsumption higher than 5V / 1A. Very old HDDs with 4200RPM and a size smaller than ~40GB may fulfill the USB specification. Even newer 4200RPM HDDs need more than 500mA during spinup.