The Pentium D 800 series equals two Pentium 4 600 dies on a chip, but with only 1 MB L2 cache per core. All other features of the Pentium 4 600 series were retained. Since two processing cores require more power than a single one and the power envelope of 130 W imposes a restriction, clock speeds had to be reduced a bit. As a consequence, the fastest model was the Pentium D 840 at 3.2 GHz, with the Pentium D 820 at 2.8 GHz being the entry-level dual core. Our Pentium D 800 at 3.0 GHz, which is model 830, provided slightly more performance than the Pentium 4 630, but also required the most power of all processors in our lineup: 215 watt-hours is a lot, especially when compared to the 106 watt-hours of the Core 2 Duo E6850.

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We used a Pentium D840 (3.2 GHz) and set it to 3.0 GHz (Pentium D 830).

With Enhanced SpeedStep enabled, a Pentium class FSB800 processor on Socket 775 will reduce its idle clock speed to 2.8 GHz. In case of the Pentium D 830, this is not much of a difference compared to the default clock speed of 3.0 GHz.

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.