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USB 3.0 external 3.5" drive without power adapter?

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March 13, 2012 3:24:27 PM

Is it possible to have an External USB 3.0 enclosure (for Sata 3.5" HDD) with no power adapter requirement??? Most of the External enclosures I've seen on Newegg have a power adapter. (I see some 2.5" models without them though.) Is this for backup/extra boost or is it needed?

I'm on my last decision before buying all the parts needed for my new system build. The last part: The desktop case.

The difference: The front port either has eSata or USB 3.0 connection. eSata is faster so if I need a power adapter anyway than who needs the USB 3.0?? Know what I mean? :) 

3.5" USB 3.0 Enclosure

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a c 371 G Storage
March 13, 2012 3:29:45 PM

I don't think a USB port can provide enough power for a 3.5" drive, thus the need for a power supply.
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a c 289 G Storage
March 13, 2012 3:46:54 PM

Hawkeye: Didn't USB 3.0 increase the available power? Yes, the OP should use a drive with a separate power supply, but...

USB 3.0 increased the power from 0.5 watts to 0.9 watts at a nominal 5 volts. Still pretty tight for a 3.5" HDD, at under 5 watts.
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a c 371 G Storage
March 13, 2012 3:52:48 PM

WyomingKnott said:
Hawkeye: Didn't USB 3.0 increase the available power? Yes, the OP should use a drive with a separate power supply, but...

USB 3.0 increased the power from 0.5 watts to 0.9 watts at a nominal 5 volts. Still pretty tight for a 3.5" HDD, at under 5 watts.


Yes they did. I wish they had boosted it just a bit more. You might be able to get away with using USB power alone, but as you stated, it will be tight. If the manufacturer provides a power adapter, then I assume it won't be able to draw enough power from the USB port.

If the OP is willing to trade off a 3.5" drive for a 2.5" drive, then he'll have more options available.
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a c 289 G Storage
March 13, 2012 4:24:22 PM

I've got two 2.5" USB 2.0 drives that require that g*d-awful Y cable to draw power from two USB ports. I usually plug them into a powered USB hub that I have that's way out of spec - it provides massive amounts of power if the drive tries to pull it.
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a c 288 G Storage
March 14, 2012 7:40:24 AM

A USB port provides power at +5V.

A 3.5" drive requires +5V and +12V power. I haven't heard of any external enclosure that steps up a +5V input to +12V. Plenty of +12V enclosures go the other way, though.
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March 14, 2012 4:13:41 PM

Thanks guys.
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a c 289 G Storage
March 15, 2012 11:57:32 AM

So many times I've wished that I had DC 5V and 12V outlets in my home office...
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March 25, 2012 1:52:25 AM

Best answer selected by gggirlgeek.
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