Power consumption
We measured system power consumption, sans monitor and speakers, at the wall outlet using a Watts Up Pro power meter. Power consumption was measured at idle and under a load consisting of a multi-threaded Cinebench 10 render running in parallel with the "rthdribl" high dynamic range lighting demo. Results that fall under "No power management" were obtained with Windows Vista running in high-performance mode, while those with power management enabled were taken with Vista in its balanced performance mode.

We ran the X58 Eclipse with and without its GreenPower energy saving scheme enabled, and found that it saves about eight watts overall. Even without GreenPower, the Eclipse still consumes less power than the other boards when under load. The EX58-UD5, on the other hand, has the highest power consumption of the lot. Gigabyte's Dynamic Energy Saver software should be able to lower the UD5's power consumption a little (we've seen up to an 8W drop in power consumption on other Gigabyte boards), but since DES software isn't yet compatible with the UD5, we were unable to measure its impact.

Overclocking
Enthusiasts hungry for Core i7 processors are likely to select the 920, which is by far the most affordable of the bunch. Since this chip lacks an unlocked upper multiplier and is hampered by an arbitrary memory speed ceiling (at least until motherboard makers find a way around that particular limitation), we've focused our overclocking attention on pushing the base clock of each board. To take the processor out of the equation, we dropped the CPU multiplier to 12X before cranking on the base clock, testing for stability with an eight-way Prime95 load along the way.

190MHz on the X58 Eclipse

Although we initially set a static 6X memory multiplier to drop the Eclipse's memory bus speed, we found that leaving this setting at "auto" actually produced better results. In fact, with the board set to manage the memory bus speed on its own, the Eclipse effortlessly sailed up to a 180MHz base clock. 190MHz wouldn't post until we set the QPI link to "slow-mode," but it was perfectly stable once we did. However, even with slow-mode enabled, the Eclipse couldn't avoid BSODs under load with a 200MHz base clock. Playing with chipset, QPI, and other voltages didn't help, either. Since a 190MHz base clock will take a Core i7-920 up to 3.8GHz, we're not inclined to complain too loudly.

In order to get the UD5 to run a 6X memory multiplier, we were forced to leave the uncore multiplier set to "auto." This apparently wasn't a problem for the board, which like the MSI, cruised up to 180MHz without making a fuss. 190MHz was a little more problematic, with the UD5 posting but crashing under load. Fortunately, switching the QPI link to "slow-mode" quickly remedied the problem, allowing us to hit a stable base clock of 200MHz. The UD5 posted at 210MHz, too, but quickly crashed under load, no matter what we did with system voltages.