If it isn't on the list, then it won't work. Besides why would you want to use a P4 640? If you have no choice, then get a used motherboard that officially supports it.
That info is available at Intel. A P4 640 3.2Ghz isn't on the list of supported processors. The specs of both motherboards seem to be identical, but the dg41ty could includes a parallel port and a DVI-D port.
If it isn't on the list, then it won't work. Besides why would you want to use a P4 640? If you have no choice, then get a used motherboard that officially supports it.