I have the same question - assuming I don't care how it looks - what are the best stats to look at? Some options are -
16GB - 4x4GB CAS 9 9-9-9-9-24 Corsair CMZ16GX3M4A1600C9
16GB - 2x8GB CAS 10 10-10-10-10-27 Corsair CMZ16GX3M2A1600C10
Which is the fastest configuration? CAS 9 will be faster than CAS 10, but is it negligible? Is a 4x4 configuration faster than an 2x8 configuration for the same CAS latency?
the 4x4 GB kit is better. You get the same amount of ram with either route. But 9 CAS latency is better and aesthetics the 4 x4gb sticks look better than two lone wolf sticks.