Nano light issue

ok so heres a weird one
just plugged up my nano system and although its all functioning , none of the lights on the nano work as in choose ,blind ,clear etc also the desk lamp.
when I plug the PSU in I can see the red leds on the board light up , done a panel test and all bar lights work
only thing I have changed is upgrade to win 8.1 and H4 2.5
bit lost