High power bills? It could be your PC....

No, really.

If you have a new or fairly new computer, and you've noticed your electrical bills go through the roof, your PC could be to blame.

While PCs today have reached a degree of technical sophistication and processing power unheard of only a few years ago, the price for performance seems to be electrical power, and lots of it.

It used to be that when buying or building a new PC, the primary considerations were performance, and cost. Nowadays, you have to factor in power consumption as well. If you're the type who leaves his or her PC on all the time, which is isn't really unheard of in these times with the popularity of broadband internet access, the cost of electricity can really add up significantly over time.

And the two biggest culprits are the brains of your PC, the Central Processing Unit (CPU), and (to a lesser degree) your video card (see earlier post here).

As far as contemporary CPUs are concerned, it seems that Intel processors are the worst offenders. To illustrate, here are the TDP (Thermal Design Power) figures (in watts) for low-end to high-midrange processors currently available here in the Philippine market (availability based on PC Express' product list):

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Intel Celeron D 331 (2.66 GHz)1 - 84 watts
Intel Celeron D 336 (2.8 GHz)1 - 84 watts
Intel Pentium 4 506 (2.66 GHz)1 - 84 watts
Intel Pentium 4 511 (2.8 GHz)1 - 84 watts
Intel Pentium 4 630 (3.0 GHz)2 - 84 watts
Intel Pentium 4 640 (3.2 GHz)2 - 84 watts
Intel Pentium D 805 (2.66 GHz)3 - 95 watts
Intel Pentium D 820 (2.8 GHz)3 - 95 watts

1Prescott core.
2Prescott 2M core.
3Smithfield core (dual-core).

Note: All of the processors listed above utilize the Socket T or LGA 775 socket interface.

For comparison, here are the TDP figures for current AMD processors currently available in the Philippine market as well (availability based on PC Express' product list):

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Sempron 2500+1 - 62 watts
Sempron 2600+1 - 62 watts
Sempron 2800+1 - 62 watts
Sempron 3000+2 - 62 watts
Sempron 3100+2 - 62 watts
Athlon 64 2800+3 - 89 watts
Athlon 64 3000+4 - 51 watts (Socket 754) 67 watts (Socket 939)
Athlon 64 3200+4 - 59 watts (Socket 754) 67 watts (Socket 939)

1Palermo core.
2Palermo/Paris core.
3Newcastle core.
4Venice core.

Note: All AMD processors listed above utilize the Socket 754 socket interface except for the Athlon 64 3000+ and 3200+ which are offered on both Socket 754 and Socket 939.

You will notice that except for the Athlon 64 2800+ (which is based on an older fabrication process), AMD processors typically consume less power than their Intel counterparts. AMD does not offer a dual-core processor equivalent to Intel's Pentium D 805 and 820, but for comparison, AMD lowest speed grade dual-core processor, the Athlon 64 X2 3800+, consumes 89 watts of power, which is 6 watts less than that used by lower end Pentium D processors. Interestingly, the Athlon 64 X2 3800+ is also significantly more powerful as far as processing is concerned, hence the higher model number designation.

Some of Intel's high end single core offerings, particularly those using the Prescott core running 3.4 GHz or higher could actually use up to 115 watts. As you would imagine, such processors would require aggressive cooling solutions to keep the heat in check. Now imagine running a PC with such a CPU installed running eight hours or more a day.

It's worth noting that most, if not all of the higher end processors (and some of the low end processors as well) from both Intel and AMD feature advanced power management technologies. Intel calls its power saving features SpeedStep®, AMD calls theirs Cool'n'Quiet™. While these technologies can lower power consumption significantly during idle periods, when the processor is active (which is to say, most of the time you're doing something) you'll still end up maxing out the power draw of your CPU whether you like it or not.

So what now?

Taking all of the foregoing information into consideration, here are some tips you may find useful when selecting what processor to choose for the next computer you build/buy:

  1. Don't buy more processing power than you need. Sure, you can splurge on the latest high speed single or dual-core processors, but if you really don't need the additional muscle, you'll just end up paying a premium with the initial purchase (the higher cost of the high-end processor, as well as the cost of a high wattage power supply, which is often a requirement when running high-end processors), not to mention the electrical bills you may incur in the long run;

  2. You should know that power consumption also has a direct correlation with heat production. Processors which consume more power invariably generate more heat, necessitating more robust cooling solutions and perhaps more fans. Processors with low power consumption run cooler;

  3. You may or may not be an AMD fan, but it can't be denied that AMD processors run cooler. While most newbies and tech unsavvy folk are often blinded by the Intel brand and therefore tend to gravitate towards one of their offerings, most techies in the know, and the vast majority of DIYers go AMD. AMD processors are at least as fast as their Intel counterparts, and oftentimes faster. In case you haven't heard, the argument about gigahertz being directly proportional to performance has long died, and clock frequency is no longer an effective indicator of relative performance as it once was. AMD processors are also usually cheaper. For example, an Athlon 64 3000+ costs about P6,800.00. A 3 GHz Pentium 4 cost about P9,000.00. While Sempron processors are a smidge more expensive than their counterpart Celeron processors, it should be noted that Semprons (the Socket 754 versions, not the older Socket A ones) are generally considered more powerful processors than Celerons according to most benchmarks;

  4. Whatever processor you buy, make sure that you enable the power management technologies that it supports. You are sure to save a few watts here and there if set up correctly;

  5. If you're really hardcore about saving electricity, get a laptop instead. Mobile processors, such as Intel's Pentium M, Celeron M or AMD's Turion 64 use up even less power, from as low as 35 watts or so for the higher end models, sometimes dipping to as low as 7 or 5 watts. Of course, when the power consumption is as low as this, performance often (though not always) takes a tumble.

And me, what processor do I use?

My main PC currently has a Athlon 64 3000+ processor, the Socket 754 variant. Maximum power draw? 51 watts. A 3 GHz equivalent rated part, using 33 watts less power than a 3 GHz Pentium 4. And just as fast, maybe even faster. Imagine that.

I guess now you ought to think twice now before purchasing that multi-gigahertz processor you've so longed for.

It seems that you pay for speed, in more ways than one.


The BalusC Server | Hardware


jhay said…
Cool data! Hmmm, I wonder if you have more about the video cards. My windows pc uses an Intel Pentium 4 630 with an Nvidia GeForce FX 5900 video card.

Now for my dad's Mac G5, maybe I'll just search the web or the pinoy apple techies, my mom is starting to cry foul over our electric bills. Hopefully, the checks from adsense and text-link ads would help with the bills aside for paying for the broadband expenses.

Or maybe I should just switch to AMD processors to really ligthen up the power load?

Thanks for the great post sir Allan!
Ronald Allan said…
An Intel Pentium 4 630 uses up 84 watts.

A GeForce FX 5900 Ultra uses up 27 watts at idle, and up to 60 watts at load. A plain vanilla 5900 probably uses up slightly less power though probably not by much since the difference is only in the core and memory speeds. I use a GeForce 6800 in my gaming PC, and it uses 18 watts at idle, and 40 watts under load.

As for your Dad's G5, just to give you an idea, a 2.5 GHz PowerPC G5 uses 62 watts, which is still lower than that of the Pentium 4.

Given that your PC can draw up to 144 watts just with the CPU and GPU, a move to AMD may not be a bad idea, especially is your mom's already complaining. :-)

Glad you found this helpful Jhay. :-)

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