Unlikely for your motherboard, extremely unlikely on your CPU would work if cracked.
On both it depends on where the crack is and if the circuitry is damaged or only the package material.
You mean your motherboard and CPU have physical cracks in them? Wow, how did that happen? If the motherboard crack breaks any of the connections in the layers of the motherboard then it is dead. Near heard of a cracked CPU how is it cracked. Most likely they are both bad but you can test them and see if you lucky.