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.

Power consumption has perhaps been the single greatest weakness of nForce chipsets, and with the 790i SLI Ultra, it appears little has changed. At idle, the Ultra sucks about 15 more watts than a similarly-equipped X48 board. That margin shrinks to ten watts under load, though. The 790i is more power-efficient than its predecessor, thanks in part to the fact that it doesn't have to power an additional PCI Express bridge chip.

Don't put too much stock into these P35 power consumption results. The Asus P5K3 Deluxe motherboard we used for testing has much higher power consumption than other P35 boards.

Overclocking
For our overclocking tests, we dropped our CPU multiplier to 6X—its lowest possible value. The memory bus was also maintained at 1333MHz to keep our DIMMs running well within their limits at overclocked front-side bus speeds. Next, we turned our attention to the front-side bus, cranking it up and using a combined load of Prime95 and the rthdribl HDR lighting demo to test stability along the way.

We managed to get our test system up to a 490MHz front-side bus with the BIOS left to adjust voltages on its own. We didn't have to use the chipset's optional cooling fan, either. However, getting the system stable with a 500MHz front-side bus proved a little more problematic. Posting wasn't an issue, and neither was idling at the Vista desktop, but after about five minutes of crunching our stress test, we'd get a blue screen or system crash. Adding the chipset cooler didn't help, and neither did manually messing with chipset and other voltages.

490MHz isn't the highest front-side bus overclock we've seen from a Core 2 motherboard, but it's up there, and certainly high enough for all but the most extreme overclocking endeavors. Then again, your mileage may vary.

One area where it won't vary, provided that you spring for the Ultra variant of the 790i SLI, is with memory speeds up to 2000MHz. With a set of EPP 2.0-certified Crucial Ballistix DDR3-2000 modules, we were able to push the 790i's memory bus to an effective two gigahertz.

DDR3 is really delivering on its potential for higher clock speeds, and the nForce 790i SLI Ultra is primed for the fastest modules on the market.