There are no problems NB clock with Asus Z170/Z270, in contrast to MSI Z170/Z270 Series...
I tried the boards MSI Z170 Gaming M3/M5/M7/M9 and Z270 Gaming M5/M7 with all of them the frequency of the north bridge is read incorrectly.
This may be the problem due to bios? I pulled out the video card(EVGA GTX 1070 FTW) and the problem disappeared. At least I can not reproduce the situation with the problem...
ps. But is it right that it is indicated that there is not present thermal sensor? Because it is available, Giantec GT34TS04
CPU-Z when there was a problem not always read the data SPD... Now for now everything is fine