Asus G703gx i9 8950hk rtx 2080

Hello everyone I bought asus G703gx with i9 8950hk and rtx 2080 i have some issues with oc the cpu when I overclocked cpu to 5ghz with armoury crate I opened xtu and i see all cores be in 5ghz like i did in armoury crate when testing in cenabench r15 and open hwinfo monitor is see all cores in 5ghz but .... when tested in heaven benchmark see the cpu in 4.7ghz i wonder why and how? My bios version is 312v any ideas for best overclocking cpu