Does a USB 3.0 connection require a USB 3.0 cord?
The SuperSpeed transfer mode requires a USB 3.0 or higher cable. Earlier spec cables will still make a connection but at a slower rate.
Source 1: USB 3.0 - Wikipedia
The VBUS, D−, D+, and GND pins are required for USB 2.0 communication. The additional USB 3.0 pins are two differential pairs and one ground (GND_DRAIN). The two additional differential pairs are for SuperSpeed data transfer; they are used for full duplex SuperSpeed signaling.
Source 2: USB 3.0 Super Speeds - USRobotics
USB 2.0 cables can be used with 3.0 ports but the transfer rate will fall back to 2.0
Source 3: Are USB 3.0 cables different? - Answers - UserBenchmark
Yes, to get USB 3.0 speeds, you need special USB 3.0 cables. Yes, USB 3.0 cables are different. Even though you can connect a USB 3.0 device via a USB 2.0 cable, in order to achieve full USB 3.0 speeds you need to re-wire any existing cabling. USB 3.0 cables are generally thicker because they have nine internal wires versus four on USB 2.0 cables.
A "USB 3.0 connection" requires a USB 3.0 cable.
Some USB 3.0 devices can be connected and operated as a USB 2.0 device (at USB 2.0 speeds), using a USB 2.0 cable. However, speed is not the only issue.
There are at least three important differences in cable construction between the two standards.
Related to speed:
The USB 3.0 cable has 9 internal conductors vs. 4 in USB 2.0.
Four of the nine match the USB 2.0 configuration (two are for power and two are for signal). Connecting a USB 3.0 device with a USB 2.0 cable uses those conductors and operates like a USB 2.0 device.
The other five are signal conductors, which are used for the communication method that provides USB 3.0 "superspeed" (a good general description can be found here).
USB 3.0 cables have a limit of 3 meters vs. the USB 2.0 limit of 5 meters.
(Note that this is a practical limit. The cable can be any length as long as it meets all of the electrical requirements in the specification. The 3 meter limit is based on maximum allowable losses using the largest recommended wire size so that the cable is flexible.) source: specs
Related to power:
A USB 2.0 cable may not be adequate for a high current USB 3.0 device.
Some USB 3.0 devices draw more power than USB 2.0 devices. The power conductors in USB 3.0 cables need to be able to carry 900mA instead of 500mA for USB 2.0.
Additional information on USB 3.0 vs. 2.0 can be found here.
USB 3.0 jacks will work with older USB 2.0 cords, but at USB 2.0 speeds. The newer USB 3.0 connectors have more wires to carry the higher data rate.