The Intel Pentium D 840 was a desktop processor with 2 cores, launched in May 2005. It is part of the Pentium D lineup, using the Smithfield architecture with Socket 775. To further increase overall system performance, up to two Pentium D 840 CPUs can link up in a multi-processor (SMP) configuration. Pentium D 840 has 2 MB of L2 cache and operates at 3.2 GHz. Intel is building the Pentium D 840 on a 90 nm production process using 169 million transistors. The multiplier is locked on Pentium D 840, which limits its overclocking capabilities.
With a TDP of 130 W, the Pentium D 840 consumes a lot of power, so good cooling is definitely needed. Intel's processor supports DDR1, DDR2 and DDR3 memory with a dual-channel interface. For communication with other components in the system, Pentium D 840 uses a PCI-Express Gen 2 connection. Although the processor doesn't come with integrated graphics, certain motherboards with compatible chipsets can provide this capability.
The SSE4 instruction set is not supported, which can cause problems with modern games, as they require that capability.