The Testbed

The Key Ideas

Since Day 1, this system was stress-tested using Prime 95 at the overclocked speed of 3.9 GHz. CPU voltage had to be increased to 1.5 V to achieve 24/7 stability. However, this resulted in an unbearable heat output which was murderous during hot afternoons.

That led me to wonder why am I running the CPU at full speed all the time, even when it's not doing anything. I could not only cut down on the heat, I could also save a few bucks on my electricity bill, just by throttling or downclocking it whenever my PC doesn't need to run at full load.

The first thing I did was enable the CPU power saving mode, and further reduce voltage by adjusting the BIOS settings. Having the ABIT µGuru at hand was pretty handy too. Unlike most motherboard monitoring utilities, the ABIT µGuru allows me to overclock on the fly!

The ABIT µGuru even handles voltage adjustment, fan speed adjustment, and it allows you to save the BIOS settings on-the-spot so you do not have to reboot just to save your new BIOS settings. This is extremely useful if you want to underclock and overclock with a few clicks in Windows. Of course, the ABIT µGuru is not completely necessary to reduce power consumption, but it helps a lot if you want to switch between different clock speeds (underclocked, stock, overclocked, etc.) at any time, without rebooting the PC.

Power usage of the PC was measured using the APC Back-UPS RS 1000VA. It is not the most accurate device, but it is capable of showing the difference in power consumption when I make any changes. If the change in power consumption is significant enough to register, then you know it's significant enough for us to bother with.