Question Which is better ?

[pctests99]

Im gonna upgrade my RAM from 4GB to 8GB

i have 4 ram slots on my pc and my ram is a 2gb+2gb
i'm going to buy another 2+2
but there was 2models one ddr3 1333MHz CL-10 for $8
and another ddr3 1333MHz CL-9 for $10
so which one should i buy and how much difference between the cl-10 and cl-9

 

[CountMike]

Im gonna upgrade my RAM from 4GB to 8GB

i have 4 ram slots on my pc and my ram is a 2gb+2gb
i'm going to buy another 2+2
but there was 2models one ddr3 1333MHz CL-10 for $8
and another ddr3 1333MHz CL-9 for $10
so which one should i buy and how much difference between the cl-10 and cl-9

Cl9 is better but you better get same as you have now for reasonable chance they work together.