Power Consumption

As always, we measured power consumption of the entire system at the wall outlet. First up is power consumption with the test system at idle. Here AMD's Cool 'n Quiet and Intel's EIST really come into play and do their best to reduce power consumption:

System Power Consumption while Idle

As you can expect, based on the old 90nm Smithfield core, the Pentium D 805 isn't exactly the coolest running chip on the block. In fact, the Athlon 64 3000+ consumes less power under full load than the Pentium D 805 does with both of its cores idling. Note that the higher power consumption on the two Opteron parts is because Cool 'n Quiet would not work with the Opterons on our test platform.

System Power Consumption under Load

The picture doesn't get any prettier under full load. If you're expecting the Pentium D 805 to be a cool running, quiet chip, you're going to be sorely disappointed. If power consumption matters to you then you're far better off with a Pentium D 900 series or an Athlon 64 X2.

Looking at the long-term prospects, power costs money, so how long will it be before the lower power X2 3800+ reaches the break-even point? If we go with a typical $.10 per kWHr, the X2 3800+ consumes 37W less at idle and 48W less at full load. If that seems like a lot of power initially, it actually only works out to $32-$42 per year, running both systems 24/7. That means you're looking at a minimum of four years to reach equivalence in price+power. What about the 920 versus 805 power costs? The difference there is even less in terms of power use, so even at full load you're looking at $16 per year, or seven years to reach the break-even point.

Of course, you can't just look at power in most instances. The X2 3800+ will offer you faster performance during its lifetime, so it definitely warrants consideration. Lower power, lower heat, lower noise, and higher performance are all nice things to have.

Note: Pentium D 820 numbers were excluded from the power comparison due to technical difficulties with our test platform at the last minute. Based on the data here, you can expect it to consume more power than the Pentium D 805.

Gaming Performance using F.E.A.R. and Quake 4 Final Words
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  • peternelson - Sunday, April 9, 2006 - link


    Thanks Jack, that PCN was exactly what I needed.

    I had previously looked through the Intel site but not found it myself.

    Given that the physical changes were only "add 10 resistors and 2 capacitors", I wonder whether Gigabyte, Asus etc al will be modding their 975 board. Heard rumours about Asus but that their new ones won't be shipping until July? No news on Gigabyte.
  • Viditor - Sunday, April 9, 2006 - link

    Great info...thanks Jack!
  • xxtypersxx - Friday, April 7, 2006 - link

    quote:

    Interestingly enough, we found that for the most part the Opteron 165 just isn't worth it compared to the Athlon 64 X2 3800+. Thanks to AMD's on-die memory controller, the higher clock speed of the 3800+ is more useful than the larger L2 cache of the Opteron 165.


    Well I am running an opteron 165 @2.6 ghz on a 1.45vcore, and I'd say its definately worth it. And that information is blatantly wrong, as the 3800+ runs at 1.8ghz stock, same as the 165
  • JarredWalton - Friday, April 7, 2006 - link

    No, the X2 4200+ is a 2.2 GHz 512K part, the 3800+ is a 2.0 GHz 512K part, and the Opteron 170 is also a 2.0 GHz part but with 1024K. The 165 is definitely 200 MHz slower than the X2 3800+. Now, as for your quote, finish the paragraph:

    (Overclocking makes things a bit more interesting, naturally.)

    This is not an overclocking article, and if you're not going to overclock then there is absolutely no reason to spend $20 more for the Opteron 165 only to get slightly slower performance. The added cache gives a 3-5% performance boost at the same clock speed; the added 200 MHz accounts for an 11% performance boost in CPU power. It's not too difficult to see which is larger.

    That said, I have two X2 3800+ chips and an Opteron 165. The X2 chips hit 2.60 GHz, and the Opteron 165 hits about the same speed. The retail Opteron HSF is definitely better, but for serious overclocking you'd probably want to spend another $50 on an aftermarket HSF anyway. Is the Opteron 165 a bad purchase? No. It's also not the greatest thing ever to hit the planet. If I were to rate the X2 3800+ vs. the Opty 165, I have to call it a tie. Both are great chips, both overclock well, and both reach very near the same final performance levels in my experience.
  • Kougar - Friday, April 7, 2006 - link

    I've really been wanting a good definite article on ALL of these proccessors! Thank you very much! This is so handy to have as a reference when people want to know what to go with for what application/purpose. I am very much looking forward to that overclocking article, it'd be very neat to see all of these processors in it ;) Can finally see how much of the hype about Opterons is grounded in fact!

    When prices on both the 800 and 900 series plummet to next to NOTHING within several months for Conroe (http://www.dailytech.com/article.aspx?newsid=1619">LINK), this will be handy to know. Hopefully AMD will focus on fully converting over to 300mm and 65nm processes quickly to help lower their marginal costs and therefore their own retail prices.

    I did think it was rather sad to see the day when a Celeron D was fairly competetive or outright winning against a Athlon 64 3000+ though, excluding games... Guess that was just me!
  • artifex - Friday, April 7, 2006 - link

    Please include Mersenne Prime and/or distributed.net keycracking in your testing suite :)

    No, seriously, each has short benchmarks to run. And these "temporary" machines will need something to do after we all upgrade again in a few months.
  • Googer - Friday, April 7, 2006 - link

    quote:

    Pentium D 805 coupled with a cheap 945 motherboard can't be beat.


    I thought Conroe was going to run only on a 975 Chipset and early chipsets produced by Intel has a design mistake that needed to be reivised. So early spec 975 motherboards were indended to run conroe but will not, you will need a revion 2 board/chipset.
  • JarredWalton - Friday, April 7, 2006 - link

    We're not saying you can upgrade from 805 to Conroe with the same motherboard. We're saying that for about $230 you can get a reasonable socket 775 motherboard and a PD 805 and it should handle all of your multithreaded computing needs until the AM2/Conroe launches.

    975X support for Conroe is still a bit unknown - I'm not sure if early 975X boards will work, and I don't even know that all current 975X boards will work. 945 *won't* work as far as I know, as 965 will be the "value" platform for Conroe processors.
  • hoppa - Friday, April 7, 2006 - link

    I was very tempted until I saw those power ratings.... yikes.
  • kyparrish - Friday, April 7, 2006 - link

    This is the kind of article we all love reading, one that's well-detailed and concise.

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