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.
Intel unveiled the design of its Tejas processor in early 2003 with the intention of launching it clocked at frequencies of 7GHz or more the following year (Jayhawk being its Xeon counterpart).
Later, the company offered to replace processors -- but for only ... to brief the site on its forthcoming Pentium 4 technology. Essentially, Intel blackballed Tom's Hardware for reporting what ...