Quote: Originally Posted by kf10
my laptop has DDR2 PC2 6400, my father laptop has DDR2 PC2 5300, what is meant by these PC2 numbers
The terms DDR2 and PC2 are used interchangeably and means the same thing.
Your's using DDR2-800 memory, and your dad is using DDR2-667. The numbers ar in relation to the clock speed of the memory modules, and is measured in MHz. The DDR2 of the name is the type of memory, which can be either SD-RAM, DDR, DDR2 or DDR3. Most machines still use DDR2 memory, because DDR3 is still out of the affordable price range for most people.
DDR2-6400 and DDR2-800 are the same speed. 6400 is the speed at which single bits are accessed in the memory (1 bit per clock cycle), and 800 is the speed at which a full byte (8 bits) are accessed (1 byte per clock cycle). Work it out 800 * 8 = 6400.
Hope this helps.