I just built two PCs with the aforementioned Corsair SF450.
These systems are identical and both have an i7 6700k, a Gigabyte Z170N Gaming 5 and a GTX 1070.
Reason I ask is that I've noticed the fan on the psu never goes on, on neither system.
My personal system is running at 4,8Ghz (1,4 vcore)...