Higher strap problems (ram oc)

hi everyone,

i have a i7 4770k and h87 Performance from ASRock and i can't find the option to change the strap speed. i wan't to go beyond 1600mhz which is the max with standard strap. i'm currently on 1600mhz 1.5v 7-7-7-21.

i think that's the NorthBridge frequency?

i don't know???? 1.00 x 100mhz x 45 is 4500mhz. i need to change the 1.00 to 1.25 or higher. there is filter PLL Frequency but i can only set it to high or low and it doesn't change something.