HeavenKidz :
look my laptop has DDR3 memory,althought DDR3 memory says the minimum speeds is 1066Mhz but my laptop only reach 665Mhz why it can be??
any solution?
This is the marketing department at work.
Memory modules are typically marketed as "1066Mhz" or "1600Mhz" but they are (most likely knowingly) using the wrong unit of measurement.
Hz is a measure of frequency, and Mhz is a measure of frequency on the scale of one million. In digital electronics, a periodic signal is used to synchronize actions between various components. It is periodic because it repeats itself over and over again in an identical fashion. This is known as a clock signal.
DDRx-SDRAM transfers data on the IO pins on both the rising edge and the falling edge of the SDRAM clock. The data signal is not periodic, it does not follow a repeating pattern and thus it would be technically inappropriate to measure it as such. It does however transfer data at a predictable rate, twice that of the clock. The proper unit of measurement for data transfer between devices on the scale of one million is MegaTransfers per second, or MT/s.
A DDR3-1066 module performs up to 1066 MT/s per IO pin, and is synchronized by a clock with a frequency of 533 Mhz.
A DDR3-1333 module performs up to 1333 MT/s per IO pin, and is synchronized by a clock with a frequency of 667 Mhz.
This is what you are seeing. The software that you are using is reporting the bus clock frequency, and is using the correct unit of measurement. The packaging however reports the bus data transfer rate, and is using the wrong unit of measurement.
This misuse is so ubiquitous that I answer this question probably four or five times per day.