Arduino Uno output pins only 4.6V?

I triedall digital output pins to simply blink an LED, but when I meassure from the beginning to the ending of the circuit, I meassure only 4.63V. The output pins are supposed to have 5V. I know that on PWM pins the meassured voltage can be lower than the actual voltage, but therefor I tried ALL pins. They ALL are 4.60-4.63V.

Is this due to my cheap Multimeter? It is an Hapé MI-5.

Steady state Outpin pin voltage will vary from 4.2V to 5V depending on how much current is being drawn - lower for 20mA, higher for less. The 4.2V will drop even more with more current. See Sect 29 of the datasheet for Voh (V out high).

This is normal. Voltage drops when you place a load on the pin.

Search for "Pin Driver Strength" in the datasheet (it's section 29.4.8 in my copy)

Also, if you are running from USB, it is likely that there are voltage drops in the USB cable, and the fuse, and so on, that mean that the input voltage to the AVR isn't fully 5V either (measure the +5V pin,e with the same voltmeter...)