Default [Q] Can't change CPU freqvency?!

I'm on stock XXAMG4 rooted rom. Root works but I can't change CPU freq. I tried SETCpu and NoFrills but neither works. Only thing I can change is governor. I don't want to overclock my device, I want to set min. 400 mhz and max. 800 mhz but when I select those freqvency nothing happens.

Any tip?
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My devices so far:
HTC Desire
HTC Desire HD
SGS+ I9001
LG O7 P700
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SGS 3 Mini I8190 --- current
MINIX NEO X5 MINI android TV BOX