Check your power requirement is not above 20W (P=IxIxR). You measure the resistance over the coil and find the minimum voltage required (Voltage = Current (in your case 1.7A) x Resistance). You keep the 12V supply and increase the current SLOWLY and see if the motors run better. Clones maybe not but still within the range specified. Real Arduino's give exactly the required voltage. The connections IN1-IN4 are the digital control pins to/from the Arduino and the voltage should also be in the correct range. The Arduino delivers 5V which fits the range of 4.5V - 5.5V as marked in your post. Otherwise the 5V is an input from the Arduino and the jumper j8 must NOT be set. If you use 12V (Jumper J8 is set!!!), then the 5V is an output for the Arduino. The two lines you have marked are regarding the control signal from the Arduino: Use the connection as marked on your board. This is only the difference between suppliers and how they make the boards.
