Real vs effective memory clock

[julius 85]

Hi, I have come across these terms while reading some reviews and I wonder what's the difference between them. I know that real clock is 4x lower but I don't understand why.

 

[Rustyy117]

Depends on the memory used, GDDR5 you times the memory speed by 4, GDDR3 you times by 2.... the effective memory speed is the result of the memory frequency X by its relative multiple (which is dependant on the memory type)....

Thats all I know, I guess you'd have to research GDDR architechure to find out more.