why Power LED not flashing when in stand-by mode

[COMA]

hi i will be very gratefull if someone can help me understand why my power led is not flashing
at first I thought that the fault of the pc case and there is no right cable to plug
but when i finally get my dream case:wub: i find out that one is not flashing aswell
it is teh motherboard fault then ? bios ? do i can change any settings to make it work

 

[denis280]

hdd led or pwr led.what motherboard is it and case model