So I just upgraded from an i7 4790 to an i7 8700k, but I can get the 8700k to run any higher than .78GHZ except when in windows safe mode. I know its not a temp issue because I checked and it idle its about 30c and under load about 60c. I think its a driver problem some where but I don't know where exactly. When I installed all my drivers I made sure they were all correct. I really hope someone can help me as I'm getting very upset with my $700 upgrade being total Sh*t.