Where did you get those numbers from? I'm pretty sure it's supposed to be 2.5-3-3-6
Download CPU-Z from www.cpuid.com
and the memory tab will tell you the correct order of numbers and what they are called.
Go there and scroll about 3/4 of the way down the page until you see DRAM TIMINGS, it'll tell you what every number does and a lot more things you probably don't really need to know as of now