Which RAM is faster: 1333 MHz CL9 or 1600 MHz CL10?

I'm looking to upgrade the RAM in my 2.4GHz i7 (2760QM) MacBook Pro, and I'm wondering which RAM is faster - 1333 MHz CL9 or 1600 MHz CL10?

2 Answers

The 1600Mhz CL10 RAM has a higher clock speed (800MHz versus 666MHz) and a lower latency (12.5 ns versus 13.5 ns), so it's the hands down winner.

A quick shortcut to determine which RAM is faster is to check this ratio:

1600/10 = 160 1333/9 = 148 

So, even though CL10 is a higher divisor than CL9, the increase from 1333MHz to 1600MHz in the numerator is more than enough to compensate for that.