Do as
chemmajorp53 sayd.
You see, intel does not set the volts but the motherboard manufacturer does, and they set the volts high just to make sure that every cpu that gets plugged into the socket will work.
By default most Z270 motherboards (I guess thats the mobo you have with that cpu) will run a Vcore at 1.408 and that is WAY to high for a stock cpu.
If this is the case go into your bios and swap the setting on CPU Vcore from auto to manual and set it to 1.250
Most 7700k`s will post on that Vcore. If you crash or cant get into windows dont panic
Just go back into bios and set the Vcore to 1.300
If this does not help at all when it comes to temps then you have a hardware problem like
mdd1963 already sayd so no need for me to repeat it
Or you could have been one of the unlucky ones and gotten a bad 7700k chip but we can talk more about that if we cant get the temps down
(cause then we will have to force it)