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A true guru evaluates power

Power consumption then. Any videocard obviously requires a stable 12-volt power source for best performance, reliability and most of all that gaming experience of yours. We tested a lot of PSU's lately, be sure to read though a couple of reviews.

What we always do with new graphics' cards, we measure the wattage peak with the help of a wattage meter. Slight side note, you are looking at the overall usage of the entire PC.

The meter is placed between the power connector and the PSU. So please understand that using a Wattage meter is not the most reliable way of measuring power consumption. You basically look at how much power is the power circuit from your house pulling from the PSU. So you need to look at the results as being an indication and not an exact science. Let's have a look at consumption:

We moved on towards the more energy efficient Core 2 Duo (Conroe) processors recently. Okay so we used the X6800, but still.

We simply look at the peak Wattage during a 3DMark05 session to verify power consumption. You are not looking at the power consumption of the graphics card, but of the entire PC.  So then, you need 350 at the least as you want some spare wattage and 420 Watts or better is definitely recommended. When you buy a new PSU then look at the packaging and check the 12 volts rail on Ampere, it should be 22 AMPS at minimum (for the total of +12 volts rails).

If in a later stage or if you immediately decide to go for SLI then we need to redo the math. For two 7950 GT's the 420 Watts PSU could still be sufficient. But I'd really like to recommend a 520 Watt SLI-Ready PSU, preferably with dual 12 volts rails. There are some good SLI certified PSU's out there, again have a look at our PSU reviews.

Also always keep your upgrade path in mind. Do you plan to upgrade your processor to dual or quad core soon ? Going to add more HD's ? Plan to overclock ? All these factors combined will weigh in on your PSU requirements.

Please check out a couple of our many power supply reviews to get an idea okay ?

What would happen if your PSU can't cope with the load?:

• bad 3D performance
• crashing games
• spontaneous resetting PC
• freezes during gameplay
• PSU overload can cause it to break down

So many things can happen.

Dangerous Liaisons - temperatures of the graphics card

That AC passive cooling is working okay. Let's have a look at the temperatures these coolers produce. We measured at a room temperature of 22 Degrees C and then start to stress the graphics card with a couple of runs with 3DMark05.

Now then, if you buy this card then you have opted for silent cooling. There's no way that temperatures can be compared to active cooling, this is the choice you make. Including the default overclock we see an idle temperature of 59 Degrees C.

The peak temperature however is 82 Degrees Celsius. Admittedly that's quite a lot. The 7950 GT however can take it. There's actually a threshold of 125 Degrees C before the NV_SAFE sentinel will kick in and clock down the product. So for passive cooling this can be expected. It however without doubt have an effect on your manual overclock and please do not forget that this heat is dumped inside your PC.

The Accelero S1M passive cooler works as expected.

Noise Levels coming from the graphics card

When graphics cards produce a lot of heat usually that heat needs to be transported away from the hot core as fast as possible. Often you'll see massive active fan solutions that can indeed get rid of the heat, yet all the fans these days make the PC a noisy son of a gun. I'm doing a little try out today with noise monitoring, so basically the test we do is extremely subjective. We bough a certified dBA meter and will start measuring how many dBA originate from the PC. Why is this subjective you ask? Well, there is always noise in the background, from the streets, from the HD, PSU fan etc etc, so this is by a mile or two not a precise measurement. You could only achieve objective measurement in a sound test chamber.

The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBa level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement.

Who are we kidding ? This iChill card does not reproduce any sound that we can hear whatsoever. Passive cooling remember ? And since it's so silent, we must mention something about it being a nice Home Theater PC component as well. Which brings me to the next chapter.

PureVideo HDStandard and High definition Decoding

With each "new" product I always include this little snippet of text as there's a neat little trick you can pull with NVIDIA GeForce graphics cards starting at series 7. NVIDIA made the GPU (the graphics chip) an important factor in en/decoding video streams. With a special software suite called PureVideo you can offload the video encoding/decoding process from the CPU towards the GPU, and the best thing yet it can greatly enhance image quality.

PureVideo HD is is a video engine built into the GPU (this is dedicated core logic) and thus is dedicated GPU-based video processing hardware, software drivers and software-based players that accelerate decoding and enhance image quality of high definition video in the following formats: H.264, VC-1, WMV/WMV-HD, and MPEG-2 HD.

So what are the key advantages of PureVideo? In my opinion two key factors are a big advantage. To offload the CPU by allowing the GPU to take over a huge sum of the workload. HDTV decoding through a TS (Transport Stream) file, for example, can be very demanding for a CPU. These media files can peak to 20 Mbit/sec easily as HDTV streams offer high-resolution playback in 1280x720p or even 1920x1080p without framedrops and image quality loss.

By offloading that big task for the bigger part of the graphics core, you give the CPU way more headroom to do other which makes your PC actually run normal. The combination of these factors offer you stutter-free high quality and high resolution media playback. All standard HDTV resolutions of course are supported, among them the obvious 480p, 720p and 1080i modes and now also 1080P (P=Progressive and I=Interlaced). Ever since the Series 75 ForceWare driver, PureVideo is doing something I've been waiting on for quite some time now, 2-2 pull down which converts 24 frames per second to 50 frame per second PAL. But along with this the new G80 series (and this'll work on G70 as well) will offer HD noise reduction, which is great feature with older converted films. And this is where we land at Image Quality. PureVideo can offer a large amount of options that'll increase the IQ of playback. This can be managed with a wide variety of options. Obviously NVIDIA has some interesting filters available in the PureVideo suite like advanced de-interlacing, which can greatly improve image quality while playing back that DVD, MPEG2 or TS file (just some examples). Aside from that, things like color corrections should not be forgotten. All major media streams are supported by NVIDIA with PureVideo. And yes High Definition H.264 acceleration, which will become a big, new and preferred standard, is also supported.

Paradox: You do not need PureVideo for HDTV playback and connectivity, but it is recommended if you have that dedicated hardware in your system anyway.

Once you offload media streams to the graphics processor things look much better with the help of PureVideo. Have a look at the graph below where you are monitoring the CPU at work at roughly 12-20% decoding a HDTV .TS file: 

Indeed, a huge improvement over standard decoding. We are now at a CPU utilization of 12-20%, really nice for a HD MPEG2 stream. The processor is almost doing nothing. This for example is a Transport Stream file with a HDTV resolution of 1920x1080i.

In combo with the new drivers you can now also decode High Definition H.264 streams. H.264 is a compression algorithm used to transmit video efficiently between endpoints. This algorithm is seen as the replacement for its predecessor, H.263. What is different about H.264 is that it promises to deliver high quality video, H.264 also enables very high quality encoding, producing way better results than even MPEG2 and of course HDTV levels. These GeForce series 7 and 8 cards can also manage 3:2 and 2:2 pull down (inverse telecine) of SD and HD interlaced content.

New with the introduction of GeForce 8800 we see a 10-Bit display processing pipeline and also new post-processing options (works for GeForce series 7 as well):

• Adds VC-1 & H.264 HD Spatial-Temporal De-Interlacing
• Adds VC-1 & H.264 HD Inverse Telecine
• Adds HD Noise Reduction
• Adds HD Edge enhancement

With the new PureVideo engine the popular benchmark tool HQV now will score 128 points, which is near perfect.

Software like WinDVD, PowerDVD and Nero showtime will support PureVideo from within their software. You can also buy the PureVideo software for a few tenners at NVIDIA after which MediaPlayer or Media Center will work with it flawlessly. 

To give you an idea how intensely big one frame of 1920x1080 is with a framerate of 24 frames per second. Click on a the two example images above. Load them up, and realize that your graphics card is displaying that kind of content 24 times per second, while enhancing them in real-time.