Not a duplicate of this RPi.SE question, as I'll explain in a moment.
As far as I can tell, looking at my B+, there are no LEDs labeled:
10M. There are two embedded in the Ethernet port, and two on the opposite side of the board. The ones on the Ethernet are unlabeled, but I can guess what they mean. The other two are labeled
PWR only turns on once in a great while. My RPi is running just fine, and the
PWR diode is unlit (which others say should never happen). This is the one that confises me the most.
AMP seems to turn on under I/O heavy load. (Seems to be the equivalent of the old
What do these lights signify?