Windows

I've got a Dell Desktop e521, It only has a solid amber light when turned on. Everything powers on like it working, fans etc.. But the power light stays amber. Tried different memory, 3 power supplies, and 2 other motherboards, unhooked everything from the board, ie hard drive add in cards etc.. Got this other motherboard and still having same issue power light stays solid amber. I've tried the hard reset with the power unplugged and power button pushed in, same results. What am I missing? The research I've done so far says that if the power light stays solid amber it's a motherboard issue. There are no other diagnostic lights when this happens. any suggestions would be helpful. thank you.