CAS: The CAS latency is the delay between the time at which the column address and the column address strobe signal are presented to the memory module and the time at which the corresponding data is made available by the memory module.
So a lower CAS # the faster it will work, that being said I would recommend these for you.
http://uk.pcpartpicker.com/part/gskill-memory-f32133c9d8gxl they are a CAS 9 where the two pair you're looking at are a CAS 11