Step #2 : Reduce The Juice!

This is a much more drastic step to take, as you will need to sacrifice some overclockability for a greater reduction in power consumption. My tests revealed that voltage is the biggest single factor that results in higher power consumption, particularly when it's running at full load.

The table on the right shows the power consumption of my processor under idle and load conditions. The numbers are very obvious. The processor uses up a lot more power under load conditions (naturally!). What's important here is that power saving technologies like EIST or C1E can play no part when the processor is actively working on something.

Thus, the best way to reduce power consumption under load condition is to reduce the processor voltage. If your motherboard allows it, you can even choose to run your processor below its default voltage. Of course, if you want to overclock, running at the default voltage (instead of overvolting) will help you reduce power consumption. Either way though will impact the overclockability of your processor.

Take my Intel Core 2 Duo E6850 processor for example.The best it can do at stock voltage is 3.4 GHz. It can run at 3.9 GHz but only if I overvolt it. But even overvolting it at 3.4 GHz would increase its power consumption at load by 48 W (24 %).

Increasing the voltage by 500 MHz to 3.9 GHz would result in additional power consumption of 18 W, for a total of 66 W (33 %) over the 3.4 GHz processor running at stock voltage. That is a lot of power used for a mere 14.7 % increase in processor clock speed.

As you can see, most of the increase in power consumption is due to the increase in voltage (from 1.275 V to 1.505 V). Most games and applications are not able to take advantage of the increase in clock speed, so it is not worth overvolting if you do not really need the additional processing power (e.g. when you are just watching a movie or working on some spreadsheets).

Running at stock voltage in such cases makes a lot of sense because it reduces power consumption and thermal output by a huge amount for virtually no noticeable difference in performance. Even if my processor can run at 3.9 GHz, I really do not need to run it at that speed all the time. The bragging rights are hard to resist though!

Usually, I would just run my processor at 3.4 GHz, at stock voltage. It is really more than sufficient for everyday use. But when I need the extra boost in processing power, I just use ABIT µGuru to instantly switch to the overvolted profile running at 3.9 GHz. This gives me the best of both worlds - lower power consumption and better performance when I need it.

This tip will save you even more money. Using my overclocked PC as an example, running at a lower overclocked speed of 3.4 GHz without overvolting would save me about 49 kilowatt-hours of power a month. Even if I just choose not to overvolt, that would save me almost 36 kilowatt-hours of power each month.

If you intend to do the same, do note that you should also re-certify the stability of your system when overclocked at stock (or lower) voltages. Yes, you can also try under-volting your processor for even lower power consumption!