Powering a 3.5" HDD with USB?

nachamiyahu

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Feb 23, 2011
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I wanna test a hard drive without putting it into my case. My friend suggested i take the plug off one of my external laptop hard drive enclosures and put it on that so i can power the drive via USB. will that work?
 
Maybe; most likely not. Most of the times that I have checked, 3.5" spinning drives draw more watts than the USB port is designed to provide. USB 2.0, anyway.

Do your external laptop hard drive enclosures have a separate power supply too, or have you been lucky enough to drive 2.5" drives on a single USB port? Many of these products are sold with a "Y" cable that allows them to draw power from two USB ports at the same time; this suggests that one port is not enough.

Generic drive docks, like this: http://www.newegg.com/Product/Product.aspx?Item=N82E16817709029 , tend to come with a power supply.

BTW, you would get much better speed with a USB 3.0 adapter or an eSATA port; are either of these available on your PC?
 
I don't think you can power a 3.5" with USB. There are plenty of 2.5" USB enclosures that will power a drive just fine, but some of them even require the 2-headed USB cable to get enough power from USB ports to do the job. Most external enclosures for 3.5" drives some with a power brick that you plug into the wall outlet.

The easiest way to do this would be to take the side off of your case and run one of the wires from your power supply out to the drive. And you could run a SATA cable out too and not use USB. USB is much slower for accessing your hard drive.
 
i do have an eSATA port on the front of my case but i dont have any eSATA cables. i guess ill just take the side off my case and do it that way lol. i was trying to avoid that cuz i wanted to be lazy lol. Oh btw. i do have an external hard drive case. couldnt i take that a apart and use that instead?
 

No. Specs for USB 2.0 say that the port can provide up to 500 ma. at 5 volts. This is more than adequate for a 2.5" laptop drive. A 3.5" drive also needs 12 volts.
 

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