Intel Core 2 with Various FSB/Memory Clock Rates
 

In case of popular Core 2 processors with 1066/1333MHz FSB, it makes sense to use dual-channel memory of much higher bandwidth than the nominal FSB can provide. If we consider DDR2-667 the reference point, fast DDR2 or DDR3 memory can bring a 6-8% performance gain in real applications.

http://ixbtlabs.com/articles3/mainbo...2-ddr3-p1.html