Sort of: The Pentium 4 was a strange chip. It had way too many pipeline steps, and was basically just chasing high clock speed marketing numbers instead of performance. In other words, it hit "3.2GHz" by cheating.

I'd argue you'd need to use AMD's Athlon XP or 64 bit processors, or either Pentium 3 / Core 2 Duo to figure out when clock speeds stopped increasing.