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Power consumption
We measured system power consumption, sans monitor and speakers, at the wall outlet using a Watts Up power meter. Power consumption was measured at idle and under a load consisting of a multi-threaded Cinebench 9.5 render running in parallel with the "rthdribl" high dynamic range lighting demo.

The Core 2 Duo's C1E Enhanced Halt State doesn't appear to be working properly on the P35 Platinum. We could only get the board to throttle processor clock speeds when we used Vista's "balanced" power management setting, but that invokes clock throttling through SpeedStep rather than C1E.

When we first reviewed Intel's P35 Express chipset with Asus' P5K motherboards, we were alarmed to see just how much power the chipset appeared to consume compared to its rivals. We decided to reserve judgment until we could see the chipset in action on other boards, and it's a good thing we did. The P5K and P5K3 Deluxe consume considerably more power than the other P35 boards, particularly at idle.

The Gigabyte and Abit boards prove the most frugal when it comes to power consumption, with each taking a turn at the front of the pack. The P35 Platinum does well here, too, but its idle power consumption is a little high, even when SpeedStep is throttling clock speeds.

Note also that DDR3's potential power saving attributes don't show up in the P5K3 Deluxe. Despite the new memory type's lower operating voltage, the P5K3 consumes more power at idle and under load than the P5K.

For our overclocking tests, we swapped in a retail Core 2 Duo E6300 processor and lowered its multiplier to 6x. Next, we backed off our memory timings and dropped the FSB:DRAM ratio to 1:1—the lowest available setting on each board.

Turning our attention to the front-side bus, we stepped up in 10MHz increments until the system was no longer stable looping Prime95 and the rthdribl HDR lighting demo. We were able to hit the following front-side bus speeds with each mobo:

  • Abit IP35 Pro — 490MHz
  • Asus P5K Deluxe — 490MHz
  • Asus P5K3 Deluxe — 490MHz
  • Gigabyte GA-P35-DQ6 — 490MHz
  • MSI P35 Platinum — 490MHz
Somewhat surprisingly, all five boards hit a front-side bus speed of 490MHz with our E6300, suggesting that the CPU itself may not be capable of running at higher bus speeds. 490MHz is the fastest front-side bus we've had running with this processor, and no amount of fiddling with voltages could coax our systems to boot at 500MHz.

490MHz on, well, take your pick

We should note that although each board hit 490MHz, only four reached that milestone without additional voltage. The IP35 Pro needed an extra millivolt running to the processor to maintain stability with front-side bus speeds above 470MHz.

As is always the case with overclocking, success depends on numerous factors, including the mix of system components, luck, and the freshness of your virgin sacrifice. Your mileage may vary.