I have a Lenovo thinkcentre m57p 9088. Anyone know what is the Max ram?

The Manuel says the max ram is 8gb, with 4 slots, 2gb's each. However the motherboard supports pc2-6400 ram which can come in 4gb sticks, Is it possible that this board can support a 4gb ram stick?

Read more: I have a Lenovo thinkcentre m57p 9088. Anyone know what is the Max ram?