Force CPU full with display black i have a galaxy core duos and minergate instaled for test, however, my H/s in on display stay in 7 and in off stay in 0,5, i instaled overclock app however did not work.

how to force CPU full speedy in off display?

Samsung did this on a galaxys s3 rig
You can force your cpu to work at full speed by changing the governor to Performance. If you are not sure what a governor is, you need to have ROOT ACCESS then you can use an app named Kernel Adiutor(https://play.google.com/store/apps/details?id=com.grarak.kerneladiutor&amp;hl=en) to change the cpu governor. 

Also, overclocking would require a custom kernel which you can find at XDA Forums.

Found these relevant guides:
Tomsguide:https://www.tomsguide.com/us/overclock-android-device,review-1762.html

Androidpit: https://www.androidpit.com/how-to-overclock-android