Just installed i7 7700k on ASUS Z270 Prime-K and the CPU clock I get is 3.8GHz instead of 4.20GHZ. My current BIOS version is 0316 and I know there is available BIOS update BUT it doesnt mention that fixes this issue. Had i5 7500k on this mobo before, was working fine. Is it CPU issue or MoBo issue ?