I want to do a 8GB Ram upgrade on a 2011 MacBook Pro. Crucial has two kits available. MacBook Pro 2.3GHz Intel Core i5 (13-inch DDR3) Early-2011 http://www.crucial.com/store/listpa....3GHz+Intel+Core+i5+(13-inch+DDR3)+Early-2011 8GB Kit (4GBx2) DDR3 PC3-10600 CL=9 Unbuffered NON-ECC DDR3-1333 1.5V 512Meg x 64 Part #: CT1895171 and 8GB Kit (4GBx2) DDR3 PC3-10600 CL=9 Unbuffered NON-ECC DDR3-1333 1.35V 512Meg x 64 Part #: CT2336212 Which one is better? And why is there two types? Would using the 1.35V get better battery life or have less performance?