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POWER
The power consumption of an add-on video card can be estimated by comparing
the total system power draw with and without the card installed. Our results
were derived thus:
1. Power consumption of the graphics card at idle - When CPUBurn is
run on a system, the video card is not stressed at all, and stays in idle mode.
This is true whether the video card is integrated or an add-on PCIe 16X device.
Hence, when the power consumption of the base system under CPUBurn is subtracted
from the power consumption of the same test with the graphics card installed,
we obtain the increase in idle power of the add-on card over the
integrated graphics chip (Intel GMA950). (The actual idle power
of the add-on card cannot be derived, because the integrated graphics does draw
some power — we'd guess no more than a watt or two.)
2. Power consumption of the graphics card under load - The power draw
of the system is measured with the add-on video card, with CPUBurn and FurMark
running simultaneously. Then the power of the baseline system (with integrated
graphics) running just CPUBurn is subtracted. The difference is the load power
of the add-on card. (If you want to nitpick, the 1~2W power of the integrated
graphics at idle should be added to this number.) Any load on the CPU from FurMark
should not skew the results, since the CPU was running at full load in both
systems.
Both results are scaled by the efficiency of the power supply (tested
here) to obtain a final estimate of the DC power consumption.
|
Estimated Power Consumption Comparison (DC)
|
|
Card
|
Idle
|
Load (ATITool)
|
Load (FurMark)
|
|
Sparkle GTS 250 1GB
|
22W
|
87W
|
124W
|
|
PowerColor HD 5850 1GB
|
21W
|
78W
|
132W
|
|
ATI HD 4870 1GB
|
67W
|
121W
|
134W
|
|
Asus GTX 260 896MB
|
35W
|
122W
|
145W
|
|
HIS HD 4890 Turbo 1GB
|
71W
|
124W
|
149W
|
|
HIS HD 5870 Turbo 1GB
|
23W
|
109W
|
215W
|
By our estimates, the HIS 5870 Turbo requires a massive 215W when being stressed
to the limit using FurMark, making it far away the most power hungry card we've
come across. On the bright side, like other members of the HD 5000 series, the
5870 has very low idle power requirements.
Video Playback
|
Test Results: Video Playback
|
|
Test State
|
PowerColor HD Radeon 5850
|
HIS HD Radeon 5870 Turbo
|
|
Avg.
CPU
|
Avg. DC Power*
|
Avg.
CPU
|
Avg. DC Power*
|
|
Rush Hour
(1080p H.264)
|
5%
|
+25W
|
5%
|
+28W
|
|
Coral Reef
(WMV-HD)
|
27%
|
+44W
|
28%
|
+40W
|
|
Spaceship
(1080p x264)
|
3%
|
+22W
|
3%
|
+25W
|
|
*compared to idle
|
As the 5870 has similar idle power as the 5850 and the same UVD 2.0 chip, video
playback was almost identical between the two cards, both in terms of CPU utilization
and power draw. Like the 5850, it exhibited an odd quirk during our WMV-HD clip.
The HIS 5870 Turbo has clock/memory frequencies of 157/300 MHz when idle, 875/1225
MHz on load, and 400/900 MHz when UVD is doing its thing. During WMV-HD playback,
it continually hopped between these three states rather than standing firm at
400/900 MHz like the other two clips. This is accounts for some of the difference
in power consumption.
|
GPU-Z: Clock speed irregularities during WMV-HD playback.
|
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