No physically problem, the pc simply don't start and I see the message "no HDMI1 selected" on the screen.And it doesn't work if I try to select another HDMI, DVI either.
The cpu is i7 850
The socket is s1156 and it fit the socket.
Your motherboards cpu support list doesn't mention i7-850 as being compatible. It does show i7-860 though so sounds like you need to update the bios with the old cpu before installing the new cpu.