Power Consumption
We have spoken a lot of power consumption lately with ASUS mainboards being a negative example. Once the processor core voltage on these mainboards is changed, Intel power-saving technologies stop working. In the meanwhile, Vcore often needs to be increased for the sake of better overclocking results. However, mainboards on Nvidia chipsets turned out to be wasting even more power.
ASUS mainboards have “smart” BIOS. During relatively low overclocking to a certain point, it doesn’t interfere. At higher frequencies it starts increasing processor Vcore, Vmem, Vchipset: the higher you overclock, the more the voltages increase. Reference mainboards on Nvidia chipsets cannot boast a smart BIOS. Even during insignificant processor overclocking (for example, from 1333MHz FSB to 1350MHz) it will immediately increase the processor, FSB bus and chipset voltages. After that these voltages do not increase any more for the sake of further successful overclocking, no matter how far you push the frequencies, however, this initial increase is more than enough for Intel power-saving technologies to shut down. Too bad.
Nvidia based mainboards have always been known for their power-hungry temper, and during overclocking their power consumption rates will depends a lot on the voltage settings. For the sake of fair comparison we will measure power consumption wit the CPU working in its nominal mode, when the power-saving technologies work on all boards.
For this test we used Extech Power Analyzer 380803. It is connected even before the power supply unit, so the results it shows reflect the power consumption of the entire system without the monitor. We used processor FPU-test from S&M 1.9.1 utility to check the power consumption under load.
Nvidia nForce 790i Ultra SLI based mainboard consumes a little more power than Intel X38 Express based board, however, the difference is really small. Nvidia chipsets will most likely become more economical with the time, but even at this point, power consumption doesn’t determine the chipset choice. What is truly remarkable, that the mainboard based on a flagship core logic set consumes considerably less power than a board on a more mainstream chipset from the same series! This can certainly be partially explained by lower power consumption of DDR3 SDRAM DIMMs, however the main power-consuming knot on the Nvidia nForce 750i SLI based mainboard is definitely the Nvidia nForce 200 bridge. As you remember, Nvidia nForce 790i Ultra SLI doesn’t have it. Aren’t you surprised that ASUS claims its P5N-D mainboard boasts great energy efficiency? However, ASUS P5N-D mainboard is not the topic of our today’s review, we have already discussed it in one of our previous articles.
