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I'm currently buying some new USB micro cables for my Samsung Galaxy S5. It supports both USB 2.0 micro and USB 3.0 micro connectors.

Will I see better charging times when using the USB 3.0 cable connected to a wall charger vs. a USB 2.0 cable? I would assume not, but I'm not sure. AFAIK, not too many things draw any more than 2A.

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Theoretically, you shouldn't, since wall chargers can supply the same amount of current over a USB 2.0 cable as a USB 3.0 cable.

However, you might see a difference in difference in charging times due to the electrical properties of the cables. Because the USB 3 spec calls for a higher maximum current than USB 2 (950 mA vs. 500), it stands to reason that USB 3 cables will be better constructed and thus able to conduct higher amounts of current than run-of-the-mill USB 2 cables. See this Reddit thread for more information.

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As with most things, it depends - most phone chargers have delivered > 1 A current for a while now (some going > 2 A) over USB 2.0 cables. A properly specced cable is probably fine; the higher current capability of USB 3.0 is mostly dependent on the host, not the cable. But cheaper cables tend to skimp wherever possible, and may be an issue - I have a cheap USB 2.0 extension cable here with a voltage drop of > 1 V over a metre... – Bob May 26 '14 at 23:07

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