Power Consumption, Temperature, Noise, Overclockability
It is the first time that we have ever had an asymmetric dual-processor graphics card and we want to know how much power it would need in different applications. We measured its power draw on a testbed configured like follows:
- 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 is uses a card designed by one of our engineers, Oleg Artamonov, and described in his article PC Power Consumption: How Many Watts Do We Need?. This device facilitates and automates the measurement process.
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 for EVGA and XFX solutions:
The EVGA GeForce GTX 275 CO-OP PhysX Edition is far from economical as it needs two times as much as an ordinary GeForce GTX 275 even in idle mode. Both external power lines are loaded in the same measure, which means that both cores, the main G200b and the auxiliary G92b, are active even though the latter does not have any work to do in this mode. The G92b is identified by the OS as the GPU of a full-featured GeForce GTS 250 and thus receives the full ration of juice with the ensuing consequences.
Only the main core is working during video playback while the current on the power line of the auxiliary core remains the same. As a result, the peak power consumption is over 100 watts in this mode, which is not good, especially compared to AMD/ATI’s solutions. In the gaming mode the peak power draw of the EVGA GeForce GTX 275 CO-OP PhysX is the same as that of the reference GeForce GTX 275 because Crysis Warhead does not support PhysX. The 6-pin connector is loaded heavily, however. It means that this connector is not only limited to powering the auxiliary GPU. As for OCCT: GPU, the EVGA card has a lower power draw in that test than in Crysis Warhead.
As opposed to the EVGA card, the XFX Radeon HD 5850 Black Edition makes use of the advanced power-saving features implemented in the ATI Radeon HD 5000 series. Yes, it is less economical in the idle mode than the Radeon HD 5870 but the difference is a mere 1 watt. Its peak power consumption is 17 watts, which is much better than the EVGA card’s 52 watts. The red team wins in the HD video playback mode where XFX is two times as economical as its opponent. The difference in the gaming mode is obvious: 122 against 219 watts. We should note that the XFX has a power draw of over 150 W under the synthetic OCCT: GPU test, but the EVGA card consumes more than 200 W then, anyway. That’s the effect of the outdated technologies employed in the latter.
The top power connector is always loaded more than the bottom one and its peak load is 90 W, which is higher than the recommended maximum of 75 W. Such a high load is unrealistic, though, whereas the power draw of 57.6 W we observe in Crysis Warhead is within the required limits. So, there is nothing to worry about. Every high-quality power supply should cope with the XFX Radeon HD 5850 Black Edition. It does not even have to have a very high wattage rating. Stable output voltages are more important.
The EVGA card is overall just as good as an ordinary GeForce GTX 275 in terms of power consumption, but only when it comes to gaming. It is less economical under low loads. The GeForce GTX 275 CO-OP PhysX is not a good choice if you care about how much power your computer consumes when playing video or working in Windows applications. The old Radeon HD 4890 looks more power-efficient while the new Radeon HD 5770 leaves no chance to the EVGA card when it comes to power consumption.
The XFX Radeon HD 5850 Black Edition looks better in this test. Its consumption is never higher than 170 W even under an extremely high synthetic load. Under real-life loads it will consume no more than 130 watts. And its power draw in 2D mode is very low, too.
The temperatures are all right. The main GPU of the EVGA card is no higher than 75°C under load while the auxiliary GPU is not hot at all. So, EVGA may have been right in picking up the GeForce GTX 295 cooler for this card. The XFX Radeon HD 5850 Black Edition is somewhat disappointing. Its GPU is as hot as 80°C under load. This result is due to the pre-overclocked frequency and the smaller heatsink compared to the Radeon HD 5870 cooler.
And here are the results of our noise measurements.
Alas, the acceptable temperature of the EVGA card is achieved at the expense of silence, especially in 3D mode. At a background noise of 37dBA, the noise-level meter reported 49dBA at a distance of 1 meter from the working testbed! The card is even louder than a Radeon HD 4890. The rather low level of noise in 2D mode cannot save the day because the main purpose of this graphics card is gaming. The XFX is quiet in ordinary mode but becomes audible under load. It remains much quieter than its opponent, though. The difference between them is 3 dBA (at a distance of 1 meter from the testbed) which means a twofold difference in sound pressure because the decibel is a logarithmic unit. Thus, the XFX wins one more test.
As for overclocking, you can overclock both the main GPU and the physics coprocessor of the EVGA GeForce GTX 275 CO-OP PhysX. The memory banks can be overclocked individually or together, too. We managed to make our card work at frequencies of 700/1515 MHz for the GPU and 1200 (2400) MHz for the memory; the auxiliary subsystem was stable at 750/2000 MHz for the processor and 1150 (2300) MHz for the memory.
This is a rather good result but we guess that overclocking the PPU can hardly be rewarding in real-life games. We have already tested an overclocked GeForce GTX 275 in earlier reviews, so we won’t benchmark the EVGA card at the overclocked frequencies. Instead, we will pit it against other graphics subsystems that support hardware PhysX acceleration.
It was harder to overclock the XFX card. We quickly reached the top GPU frequency available in the Catalyst Control Center, raising it from the default 765 MHz to 775 MHz and there was no headroom for memory overclocking at all. Other tools refused to work with the card. It is only with the AMD GPU Clock Tool that we managed to boost the GPU frequency to 900 MHz and the memory frequency to 1200 (4800) MHz.
This is a very good result, considering that the Radeon HD 5850 is made out of lower-grade RV870 chips but you should not expect every other sample of the XFX Radeon HD 5850 Black Edition to be that good at overclocking. Now, let’s move on to gaming tests.