Pentium 4 was a line of single-core desktop, laptop and entry level server central processing units (CPUs) introduced by Intel on November 20, 2000 and shipped through August 8, 2008. They had a seventh-generation x86 microarchitecture, called NetBurst, which was the company's first all-new design since the introduction of the P6 microarchitecture of the Pentium Pro CPUs in 1995. NetBurst differed from P6 (Pentium III, II, etc.) by featuring a very deep instruction pipeline to achieve very high clock speeds. Intel claimed that NetBurst would allow clock speeds of up to 10 GHz in future chips; however, severe problems with heat dissipation (especially with the Prescott Pentium 4) limited CPU clock speeds to a much lower 3.8 GHz.