user42200: I'm working on a senior project and I am using a ATX PSU to supply power to the Arduino Yun and other components. If I'm not mistaken, its powered through the usb. I took a usb cord, strip the sheath and put the proper connections on the breadboard and connected the red wire from the PSU to the breadboard as well. When I measure it, the voltage is 5.1V max. I'm scared to hook it up to the Arduino since I read that if its above 5, it will fry it. Is this voltage fine? If not, will I have to put resistors on it to get it down? 

user42211: I would avoid directly powering any micro without voltage regulation. Things like zener diodes and dedicated regulators adds complexity. But you can pretty much power it off any positive rail at or above 5v DC.(Use nothing greater than the specs) They can also be had and implemented for very little, that and they are used on the UNO board.

user30198: It is fine. That is only 2% too high. The microcontroller is the ATmega32U4 and it can have 5.5V. The wifi module runs at 3.3V, and it has a voltage regulator. Some voltage is also lost in the cable. If the voltage is 6V, then you are in the danger zone, but not with 5.1V.
There are clones and shields of the Arduino Yún. Each has its own power supply demands. You should read what the specifications are for your board. The official Yún board requires 5V from the USB cable or 5V at the VIN pin.

42200: <p>I'm working on a senior project and I am using a ATX PSU to supply power to the Arduino Yun and other components. If I'm not mistaken, its powered through the usb. I took a usb cord, strip the sheath and put the proper connections on the breadboard and connected the red wire from the PSU to the breadboard as well. When I measure it, the voltage is 5.1V max. I'm scared to hook it up to the Arduino since I read that if its above 5, it will fry it. Is this voltage fine? If not, will I have to put resistors on it to get it down? </p>
 42211: <p>I would avoid directly powering any micro without voltage regulation. Things like zener diodes and dedicated regulators adds complexity. But you can pretty much power it off any positive rail at or above 5v DC.(Use nothing greater than the specs) They can also be had and implemented for very little, that and they are used on the UNO board.</p>
 30198: <p>It is fine. That is only 2% too high. The microcontroller is the ATmega32U4 and it can have 5.5V. The wifi module runs at 3.3V, and it has a voltage regulator. Some voltage is also lost in the cable. If the voltage is 6V, then you are in the danger zone, but not with 5.1V.</p>

<p>There are clones and shields of the Arduino Yún. Each has its own power supply demands. You should read what the specifications are for your board. The official Yún board requires 5V from the USB cable or 5V at the VIN pin.</p>
