Core 2 Duo E6850
Core 2 Duo E6850 is Intel's current dual core top model. It is based on the Core microarchitecture, which was released to the desktop space in the summer of 2006. At 3.0 GHz core clock speed, utilizing two processing cores and featuring 4 MB shared L2 cache as well as a FSB1333 bus speed, it provides high performance and an adequate power requirement that stays within the 65 W power envelope. You cannot upgrade an existing Pentium D or Pentium 4 system with a Core 2 Duo processor, so you will have to purchase a new motherboard supporting the new processors, as well as DDR2 or DDR3 memory.
Core 2 processors will reduce their multiplier to 6x in idle mode with Enhanced SpeedStep enabled. In the case of a 333 MHz interface speed (FSB1333) this results in 2.0 GHz idle clock speed. Both Core 2 Duo E6850 and Core 2 Extreme QX6850 finished the complete SYSmark 2007 run within one hour and ten minutes, but the dual core processor required significantly less power - 106 watt-hours versus 131 watt-hours for the quad core, which ran at the same core clock speed.