My long since gone A2000T(bomac) would do the same thing after afew soft resets. The Green LED would dim. Thast didn't have a PPC and had TWO power supplies. No I'm not trying to win the pissing contest, it really did have two PS...
Is there a GURU who knows what exactly causes The power light to dim? I know it does it on Reset or a crash (it will blink).
This kind of info would be good for everyone...