DDR1 is x1
DDR2 is x2
DDR3 is x4
There is two ways of looking at RAM speed. CPU-Z looks at memory frequency. The BIOS generally looks at memory clock.
You are looking at things backwards. At a memory frequency of 333 MHz, DDR2 RAM is clocked at 667 MHz. At the same frequency, DDR3 RAM is clocked at 1333 MHz.