Should be written on a label on the stick, usually looks like,
Pc3 12800 1.5v 9,9,9,24,41 2t
first bit tells you its ddr3 then the data speed limit, recommended voltage and finally the important settings that you will enter into bios,
if you look on Cpu-z's memory tab, it tells you which number is which settinghttp://www.hardwaresecrets.com/article/Understanding-RAM-Timings/26
is well worth a read though to help understand timings
**Edit, do you know what brand the ram is?