Power

We regularly look at power consumption when talking about card performance, and for this review we want to look at two different aspects of power consumption. Since these cards all have potential for home theater systems given their HDCP compatibility, we want to look at not only power consumption during game performance, but also during BD video playback.

3D Acceleration Power Consumption

It's important to be aware of how much power your card draws when gaming so undue stress isn't put on your computer's power supply. Also, high wattage power supplies have bigger fans to keep them cool; that means a card with a lower power draw might be more desirable in a system that is built for as quiet operation as possible. To test the power load of these cards during 3D acceleration, we recorded the total wattage of the system with each of the cards installed while the system was idle for reference (i.e. no programs running), and then we recorded the total wattage of the system while running a few of the demos from 3DMark06. The 3DMark06 demos put stress on the GPU and we can then compare this to the idle wattage to get a general idea of how power hungry a card is.

Idle Power



Load Power



We can see that as you would expect, higher performance cards like the Sapphire Radeon X1950 XTX as well as the EVGA and BFG GeForce 7950 GX2 saw some of the biggest power draws. The reference NVIDIA 8800 GTX required a bigger power supply than the one we used for the other cards, so we put in a more powerful one with the necessary two PCIe connectors for that particular configuration. This will make these power numbers less consistent with the others, but we can still get an idea of how power-hungry these new cards from NVIDIA are. These cards are going to require higher watt power supplies to run, and so might not be the best choice for a quiet system. We noticed that the Albatron 7900 GS had a lower power draw than the others in its class, and the Gigabyte 7600 GS was the least power-hungry of all of these cards (as well as the least effective in video decoding).

Blu-Ray Playback Power Consumption

We also want to look at power consumption while playing back a BD movie with these cards. Because 3D acceleration takes more processing power than decoding video, we will expect to see a lower power draw in these tests, but as with CPU utilization, we will probably be seeing higher power draws with future Blu-Ray and HD-DVD content which will make use of higher bitrate encoding.

We took power reading in the same way as with CPU utilization: by playing back about a minute of video from our Blu-Ray movie "Click." We are also interested in seeing the kinds of power loads these cards have when hardware acceleration is disabled in order to see the contrast between power loads. Because cards of the same family (i.e. 7900 GS, 7950 GT, etc.) saw very similar power consumption without hardware acceleration enabled, we only recorded power in this state for one of each card family. These are the results of our tests.

Bluray Playback Power Consumption - No Hardware Acceleration


Bluray Playback Power Consumption - With Hardware Acceleration


Again we see that not surprisingly, the higher performance cards see greater power draws than lesser performing ones, but we don't see a big difference here between most of the cards. In many cases, higher clocked cards of the same type see a little higher power draws than their competitors, but in some cases (like with the Leadtek WinFast PX7900 GS TDH Extreme) we see lower power draws. This tells us that there will be variation in power draw between cards of the same type depending on what types of modifications the different vendors make to their cards. Again keep in mind that we used a different power supply for the NVIDIA GeForce 8800 GTX, so it's not really an apples-to-apples comparison.

In the future, we could see power consumption go down with acceleration enabled. As graphics hardware is better suited to processing video than a CPU, efficiency should go up when using hardware acceleration. At this point, there isn't much difference, but this could change when we move away from MPEG-2 and into higher bitrate content.

CPU Utilization Heat/Noise
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  • LoneWolf15 - Tuesday, November 21, 2006 - link

    Behind Enemy Lines? Explains why Blu-Ray adoption is so slow.
  • NullSubroutine - Friday, November 17, 2006 - link

    I think ATi er AMD had been working on the drivers for GPU accelration for HD movies longer than Nvidia is all. You only have so much resources in a given department, it would make seense that Nvidia put more focus in other things (like Linux drives) where as Ati was working on this and Folding @ home stuff.
  • dickie1900 - Friday, November 17, 2006 - link

    Do you think the results will change for the 8800s when DX10 rolls out with Vista or are we going to have to wait for games to be developed that use some of the newer instructions?
  • DigitalFreak - Friday, November 17, 2006 - link

    I would doubt it. I don't believe Blu-Ray/HD-DVD decoding has anything to do with DirectX.
  • DigitalFreak - Friday, November 17, 2006 - link

    quote:

    The Calibre 7950 GT has an interesting design, with a somewhat artistic curve to the edges of the HSF, and a matte black coloring with a nice-looking silver horse and the word "Calibre" on it.


    Dude, it's a unicorn. :-)

  • phusg - Friday, November 17, 2006 - link

    First off, thanks for the great review.

    quote:

    Because the noise level of these cards was 0Db, they were not included in the graphs


    Why not? Many people just look at the graphs and this way they would miss out on the 2 quietest cards.

    Also (unrelated), it's a shame there was no mention of AGP cards. I'm sure I'm not the only one looking to stretch the life of their AGP HTPC.

    And one more thing (unrelated), aren't there initiatives that are looking to handle the HD decoding in software? I'd love a review of these. What is the slowest CPU you can decode HD content with?
  • mino - Wednesday, November 22, 2006 - link

    I second that.
    EVERY noise measurement should include reference of the bacground (system without the thingie which noise one measures).

    As those 0dB would would not be 0dB. There would be the noise of the system without the noise of the card - hence the bacground noise.

    Try to consider that in the future. No much work required for MUCH information added.
  • Spoelie - Friday, November 17, 2006 - link

    coreavc is the fastest h264 software decoder, no competition
    Their cpu-only implementation is most of the time faster than the competition WITH gpu support, but they're working on gpu support as well.

    It is payware tho.
    http://coreavc.corecodec.org/">http://coreavc.corecodec.org/
  • NullSubroutine - Friday, November 17, 2006 - link

    I originally had written this up in response to an artical that MS Office has mandatory authentication checks when doing updates. However, I think the idea of what the "intellectual property" industry is putting consumers through is rediculous.

    ....this just in, cars now 'phone home' to validate the vehicial is authentic prior to fixing factory installed parts.....refridgerator units must now be activated via phone call before the cooling units will work....lotion now comes with EULA, which is automatically agreed to at time of purchase (information is inside the bottle)....desk drawers will now automatically lock after free trial period has ended....fees must now be paid to bacteria colonies each time a user flushes the toilet....due to people stealing food, the price has increased 1000x, if the food is not authentic it will tell you, via voice, that your food is not real food, and where authentic food can be purchased if you give the food companies the information on where your not real food was purchased; when asked about the policy, supporters claimed that food was an optional luxery, paint companies now produce super ultra high quality paint products - but can only be applied with a special paint brush on special surface (microchips installed) or else the paint looks like normal paint - when cosumers were asked about the new paint they said it looked great but unless they wanted to buy all new everything, it was all meaningless...
  • shecknoscopy - Thursday, November 16, 2006 - link

    quote:

    ... the one we have for our testing is the movie "Click" which was one of the first 50GB Blu-ray discs available.


    Wow... the Blu-ray era's off to a stunning start, eh? No more complaining about the poor game options for the Wii launch, when the stunning new world of BLU-RAY is kicking off with "Click."

    Lawdy, help us.
    -Sheq

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