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mine works with 16 gb 1333 mhz. I've heard of people working even with 1600 mhz
 
16GB = 8GB x 1600 Mhz DDR3 works

Yes max you can use is 16GB = 8GB x 2 of 1600 Mhz DDR3 1.5V works

even DDR3 L 1.35v Memory works as it is back wards compatible.
 
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