The Pentium D bran refers to two series of dual-core 64-bit x86 processors with the NetBurst microarchitecture. Each CPU comprised two single-core dies (CPUs) - next to each other - in one Multi-Chip Module package. The brand's first processor, codenamed Smithfield, was released by Intel on May 25, 2005. Nine months later, Intel introduced its successor, codenamed Presler, but without offering significant upgrades in design, still resulting in a relatively high power consumption. By 2005, the NetBurst processors reached the clock speed barrier at 4 GHz due to a thermal (and power) limit exemplified by the Presler's 130 W TDP (a high TDP requires additional cooling that can be noisy or expensive). The future belonged to more efficient and slower clocked dual-core CPUs on a single die instead of two. The dual die Presler's last shipment date on August 8, 2008 will mark the end of the Pentium D brand and also the NetBurst microarchitecture.