The Inquirer speculates that chip positioning on the leaked PowerMac Motherboard may hint at an NVidia NForce 2 connection with the new PowerMacs:
The one chip in recent years to buck the trend is Nvidia's nForce northbridge, positioned at 45 degrees to a mobo's main axes. Alas the blurry snapshots of the alleged Apple product make the info printed on top of the part unreadable, but its positioning strongly suggests the inclusion of Nvidia technology.
The chip in question is pictured here (Tom's Hardware), which in this photo does not resemble the chip on the leaked PowerMac motherboard.
nForce on Apple speculation was sparked by an out-of-place reference on NVidia's nForce 2 specs pages on one feature that is not currently available on Mac systems.