I read from toms hardware :
ASRock support answer:
Dear customer,
Thank you for contacting ASRock.
According to Intel H97 chipset's specification, it doesn't support overclock on H series chipset.
And Intel already lock the OC ability on H series platform in new Microcode according to Intel’s spec, system won’t support overclock CPU after updating the BIOS P2.00 with new Intel Microcode.
If you would like to do OC on H97M Pro4, we would suggest customer to flash back the older BIOS P1.90 or earlier version with old Microcode.
Thanks
Best Wishes
ASRock TSD