I am wondering if this Arduino UNO R3 clone is clocked at 12 MHz instead of the standard 16 MHz? On the board, you can see there is 12.000 written on the crystal oscillator.
But maybe it's not the MCU clock speed? I found this other clone, which has 2 crystal oscillators?! One is 12 MHz and the other one is 16 MHz.
I can't figure out what's happening with these boards... Are these sporting faster or slower speeds? The original Arduino UNO R3 has only one 16 MHz crystal oscillator.