Motherboard light green but no boot up

i watch the whole video like 3 time and I cant find out why the the motherboard light is green but when i press the power button it dosent boot up 

i have 

rm 750 power supply 

radeon r9 270 x 

fractal define r4 black pearls 

p8h61-m-pro mother board

i7 intel

go through that and report back if nothing fixes it... last time I had a "no boot with a green light" it was a GPU driver issue, plugged it into integrated graphics and it booted fine... downloaded drivers and plugged the GPU back in...

but that's a good start for user error...

Are you sure the connections for the power switch on the motherboard are correct?  You can swap them to check (it won't hurt anything).  I always start with the easy stuff first.