because it's a penryn cpu with socket p. although it has also 478 pins, a different socket is meant in the dec. oc challenge.
the sockel 478 is a socket fot the old p4/celerons with northwood, willamette and prescott core.
i explained it in the AF forum in german as well.
edit:
cpu is already in the database:
http://www.hwbot.org/hardware/processor/core_2_t4300_2.1ghz