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?

If you choose to disregard the manual and try it, you may find that it does work. Odds of that are slim though. It will more likely just fail to boot.

It comes with 8 GB ram.