can someone explain memory speeds

[unsped]

when i run the utils i see 680mhz, but i see some people listing memory as 1800 when overclocked, are they doubling the speed or something and actually running 900mhz?

 

[AzNPinkTuv]

yes

 

[Extelleron]

900 MHz = 1800 MHz Effective
680 MHz = 1360 MHz Effective
etc, etc.............