Intel stopped using Pentium 4's NetBurst architecture and switched to Core derived from Pentium III

High power consumption and heat intensity, the resulting inability to effectively increase clock rate, and other shortcomings such as an inefficient pipeline were the primary reasons why Intel abandoned the NetBurst microarchitecture and switched to a different architectural design, delivering high efficiency through a small pipeline rather than high clock rates.

https://en.wikipedia.org/wiki/NetBurst_(microarchitecture)

https://en.wikipedia.org/wiki/Intel_Core_(microarchitecture)

Core 2 Duo https://www.businessnewsdaily.com/10817-slideshow-intel-proc...

The Intel Core line of CPUs was launched in January 2006.