The first CPU to reach a clock speed of 4 GHz was the Pentium 4 570 released in November 2004 as part of Intel's NetBurst microarchitecture, but this milestone wasn't achieved out of the box.

This means the Core i9-14900KS is now the fastest ever CPU, beating out the Core ... The 13900KF was the first CPU to break the 9GHz barrier, although just by a hair when it reached 9.008GHz.