|ASUS P8Z77-I Deluxe/WD mini-ITX Motherboard|
|Reviews - Featured Reviews: Motherboards|
|Written by David Ramsey|
|Wednesday, 14 November 2012|
Page 11 of 13
Power Efficiency Tests
The first PC I built for myself, back sometime in the 80s, used a 250 watt power supply, and frankly at the time that was overkill. Overclocked multi-GPU enthusiast systems can easly exceed 700 or 800 watts under load, and can go even higher with extreme cooling and high voltages. My test bed uses an 850 watt power supply.
Perhaps this is why all CPU and GPU vendors are imbuing their products with power-saving features, and why motherboard vendors try to add even more. And the use of these features can make a significant difference in the power use of your system.
To test the power-saving features of the ASUS P8Z77-I Deluxe/WD motherboard, I measured the power draw of the system (with no video card, and the monitor connected to the iGPU) with all the power-saving features in the EPU section of the BIOS enabled, and with all the power-saving features disabled.
The only difference I saw in power usage was under load, where turning on all EPU features including "vCore Voltage Downgrade" dropped load power from 124 watts to 87 watts. However, the vCore drop meant that all turbo features on the CPU were disabled, and it ran at 1.6GHz all the time, even under load. Obviously this had a dramatic effect on performance! This is the opposite of what I saw when testing the power saving features of the MSI MPOWER motherboard, where turning on all the power saving features reduced idle power usage and had no effect on load power usage. ASUS offers more fine-grained control of various power feature both in the BIOS and through AI Suite II, so it's possible with more fiddling around I could have achieved different results. As it is I don't see why anyone would buy a high performance motherboard like this and cripple its performance by fully enabling this feature.