[HTC 10 Questions & Answers] lagittaja:
No, the cables are not dangerous to your phone... There are no voltage problems...

If you've been reading Benson Leung's reviews of legacy type C products, the big deal is that..

..some of the A to C cables as an example don't follow the Type C specification.

Meaning they're not using a 56kOhm pull up resistor on the CC pin.

What that does is it tells the device (phone) that it is connected to a legacy A port and to draw "default USB power".

If you have a let's say a Nexus 6P and you have a type A-C cable which instead of the 56kOhm resistor has a 10kOhm resistor on the C pin.

The Nexus 6P is going to think that between it and the charger is a C-C cable > connect to 5V 1A charger and the phone is going to try and draw 3A of power even though the charger cannot support it.

If the A-C cable has the 56kOhm resistor instead of the 10kOhm resistor, it is going to tell the device that A-ha! this is a A-C cable which can be plugged into regular USB ports on desktop computers, laptops, car radio, whatever.

Now when you plug the phone in to a 5V 1A charger, it's going to pull 1A of current. Because that's what the charger supports.

If you plug it into a USB 2.0 port, it's going to draw 0.5A of current. Because that's what the port supports.

If you use a "bad cable" with a Nexus 6P which doesn't have the 56kOhm resistor, first and foremost it is going to damage the charger not the phone.

What cable to buy?

If you're looking at A to C or whatever, make sure the seller or manufacturer tells you that it has a 56kOhm resistor.

That means the cable follows the USB Type C specification.

If the seller or manufacturer does not state it has it

OR

If the seller or manufacturer refuses to tell you

OR

If the seller or manufacturer does not know

Don't buy that cable. As simple as that.

There are loads and loads and loads of proper, type A to C cables out there that properly follow the specification.

Buy one of them.

Do I want to buy USB 3.0 A to USB C cable? Does it matter?

For file transfers to computer it does matter.

For charging, NO it does not.

The HTC 10 supports USB 3.1 Gen 1 (=USB 3.0) speeds.

USB 2.0 real life transfer speed is ~30-40MB/s.

USB 3.1 Gen 1 (=USB 3.0) can theoretically do up to 5Gbit/s or 625MB/s.

Now that word theoretically is bolded with a reason. Realistically speaking we're looking at about 500MB/s max.

But again, that's just the maximum of what the USB standard can do.

The HTC 10 storage can read up to ~170MB/s and write up to ~105MB/s.

With the HTC 10 if you go from USB2.0 > 3.0 it means transfer speeds can be up to

~4.2-5.6x faster phone>>PC

~2.6-3.5x faster phone<<PC

^This assumes that your PC storage (SSD or HDD) is fast enough.^

With USB 3.0 cable you also need to go in to Settings > More > USB Connection and enable

"Fast File Transfers"

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If you want to use Quick Charge, make sure the cable you're buying is not a "charge only" cable.

Before Quick Charge works, there needs to be a digital handshake between the device and charger.

You can check this yourself, use the stock Rapid Charger 3.0 and A-C cable > plug the phone in > phone starts charging pretty much instantaneously BUT the "Quick Charger connected" text does not pop up until a few seconds after.

That was the digital handshake. It needs a couple of seconds :D
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"Charge only" cables only have 2x wires inside, they are the power wires going to VCC and GND pins.

"Charge and sync" or your every day, run of the mill, cable has at least 4x wires inside, there's the power wires (VCC, GND pins) and then there's the USB 2.0 data wires (D+, D- pins).

What that means is that the "charge only" cable cannot work with Quick Charge because there are NO DATA WIRES inside the cable.

The digital handshake happens through the data wires.

If you buy a USB cable and it does not say "charge only" then the cable is a REGULAR "charge and sync" cable.

eg. what you want.

If the cable is "charge only" it will say so!

IF you wish to not use the Quick Charge feature, then sure, go ahead and knock yourself out.

Use a "charge only" cable if you so wish. Your phone will just charge slower.