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Power Consumption, Temperature, Noise

It is interesting and important to know how much power your computer components need and consume. Therefore we pay much attention to this issue in our reviews. The new Radeon HD 6 series cards were tested on our standard power-measuring testbed with the following configuration:

  • Intel Core 2 Quad Q6600 CPU (3GHz, 1333 MHz FSB x 9, LGA775)
  • DFI LANParty UT ICFX3200-T2R/G mainboard (ATI CrossFire Xpress 3200 chipset)
  • PC2-1066 SDRAM (2x2 GB, 1066MHz)
  • Enermax Liberty ELT620AWT PSU (620W)
  • Microsoft Windows 7 Ultimate 7 64-bit
  • CyberLink PowerDVD 9 Ultra/"Serenity" BD (1080p VC-1, 20 Mbit)
  • Crysis Warhead
  • OCCT Perestroika 3.1.0

The new testbed for measuring electric characteristics of graphics cards uses a card designed by one of our engineers, Oleg Artamonov, and described in his article called PC Power Consumption: How Many Watts Do We Need?. As usual, we used the following benchmarks to load the graphics accelerators:

  • CyberLink PowerDVD 9: FullScreen, hardware acceleration enabled
  • Crysis Warhead: 1600x1200, FSAA 4x, DirectX 10/Enthusiast, "frost" map
  • OCCT Perestroika GPU: 1600x1200, FullScreen, Shader Complexity 8

Except for the maximum load simulation with OCCT, we measured power consumption in each mode for 60 seconds. We limit the run time of OCCT: GPU to 10 seconds to avoid overloading the graphics card's power circuitry. Here are the obtained results:

As expected, the Radeon HD 6870 is much more economical than the Radeon HD 5870, yet its increased GPU voltage shows up in 3D mode where it needs about as much power as the Radeon HD 5850. The new card is far more economical in the low-load modes, though. The load on the +3.3V line is surprisingly high as it hasn’t been used much in recent graphics cards. Otherwise, the Radeon HD 6870 behaves predictably in this test. We had anticipated it to load both its power connectors to the same extent. Indeed, the difference between them is negligible.

The Radeon HD 6850 behaves in a different way. It would invariably produce a result of 30-33 watts in 2D mode although the GPU clock rate, according to MSI Afterburner, was reduced to 100 MHz. We suspect our presale sample of the card didn't have the PowerPlay technology working correctly. For example, the high power consumption at low load may have been due to PowerPlay not reducing the GPU voltage. The same goes for medium loads like HD video decoding: the card proves to need more power than the Radeon HD 6870.

It is in the 3D mode, when the GPU voltage is at its maximum, that we get correct numbers. The Radeon HD 6850 needs much less power than its cousin in 3D applications, which is just what we could expect considering its lower GPU clock rate and voltage as well as the fewer number of active GPU subunits. The Radeon HD 6850 loads the different power lines just like the 6870 model, but it has only one external power connector which is loaded more as the result. This connector has a load of 80 watts in the synthetic OCCT test as the result.

Thus, the new Radeon HD series proves to be very energy efficient in our tests except for the disappointing failure of the PowerPlay technology in the Radeon HD 6850 in some modes, but we don’t think that off-the-shelf versions of the card will have that defect. The junior model of the new series needs but slightly more power than the slower Radeon HD 5770 in 3D applications whereas the senior model is as economical as the Radeon HD 5850 while being faster in modern games as promised by AMD. That’s very good, especially as the Nvidia GeForce GTX 460 1GB is not so energy efficient.

The new Radeon HD models are quite hot at work which is largely due to their not very advanced cooling systems. We must admit that most reference coolers for top-end cards deliver but mediocre performance whereas nonstandard cooling systems are generally much better. So, even though the reference Radeon HD 6870 and 6850 are far from cool, we are sure the graphics card vendors will offer them with better coolers. Besides, the temperature of 75-80°C is quite normal for a modern GPU. It shouldn't worry you at all.

As for the noise factor, the new Radeon HD 6800 cards are very quiet, nearly silent, at low loads, merging with the noise of the other components (the background noise level is 39 dBA in our test lab). But when we launch a heavy 3D application, these cards accelerate their fans and become distinctly audible. The junior model is somewhat quieter than the senior one, according to our noise level meter, but the difference can hardly be caught by ear. We wouldn’t say that these cards are loud. After all, every modern top-end gaming card is noisy. But you must be aware that you won’t have a silent computer if you purchase a Radeon HD 6870 or 6850 unless you choose a special version with a non-reference cooler.

 
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