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.

AMD chipsets have long consumed less power than their nForce counterparts, but that isn't the case with the 790GX. These results are surprising to say the least, especially given that AMD says it employed power-saving BIOS and driver tweaks developed for its Puma notebook platform in the 790GX. However, it is worth noting that our 750a-based motherboard is a relatively barebones affair with only a four-phase power solution (that doesn't officially support processor wattages above 95W) and no Firewire. The 790GX is running not only a much faster integrated graphics component, but also an onboard 128MB performance cache.

Overclocking
We haven't had much success overclocking our Phenom X4 9850 Black Edition, so we were eager to see whether AMD's fancy Advanced Clock Calibration would have an impact. To kick things off, we overclocked the CPU by raising the core multiplier on all four cores in 0.5X steps using AMD's OverDrive utility. Stability was tested at each step with a four-way Prime95 load.

As expected, our chip didn't fare so well. It cruised up to a 13.5X multiplier with little problem, yielding a stable 2.7GHz clock speed. However, running the CPU at 2.8GHz produced Prime95 errors on one core, and no amount of additional voltage was able to stabilize the chip at that speed.

Next, we enabled ACC, set it to auto, and resumed our pursuit of higher speeds. Much to our surprise, 2.8GHz wasn't a problem, even with the default CPU voltage. 2.9GHz required a voltage bump to 1.3375V, but it was stable. And so was 3.0GHz with a 15X multiplier. 3.1GHz, however, proved elusive no matter how much we fiddled with voltages.

ACC definitely works, then. We were able to squeeze an extra 300MHz from our Black Edition Phenom with what amounts to a modest voltage increase. Do keep in mind that overclocking success is never guaranteed, though.

Motherboard peripheral performance
Core logic chipsets integrate a wealth of peripherals, but they don't handle everything. To provide a closer look at the peripheral performance you can expect from the motherboards we've tested today, we've complied Ethernet and audio performance results below.

Realtek's finally built a decent Gigabit Ethernet chip in the RTL8111C, which the Gigabyte board uses to deliver excellent throughput with low CPU utilization.

Our 750a motherboard doesn't have a Firewire chip, so it's riding the pine in this test. The DS4H's Firewire performance is quite good, though.

We've switched to RMAA loopback tests that route a motherboard's stereo output through its line input, and the Gigabyte board scores higher than the XFX in several tests. That isn't enough to break a tie in the overall RMAA score, though.