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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.
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Power Consumption Comparison (DC)
|
|
Card
|
Est. Power (Idle)
|
Est. Power (ATITool)
|
Est. Power (FurMark)
|
|
Asus EN9400GT 512MB
|
11W
|
N/A
|
23W
|
|
PowerColor HD4650 512MB
|
15W
|
N/A
|
28W
|
|
ATI HD 4670 512MB
|
3W
|
50W
|
60W
|
|
ATI HD 4770 512MB
|
28W
|
50W
|
60W
|
|
ATI HD 4830 512MB*
|
18W
|
80W
|
87W
|
|
Asus EN9800GT 512MB
|
32W
|
72W
|
80W
|
|
Diamond HD 4850 512MB
|
50W
|
101W
|
N/A
|
|
* sample with unknown number of stream processors
|
Our power consumption measurements yielded mixed results. Our HD 4770 sample used
considerably more power in idle than the HD 4670 and 4830 we tested, but considerably less power than the 4850.
(See notes in the conclusions for more thoughts about the idle power.) With full 3D load, however. it drew an impressively modest 60W, 27W lower than our 4830
sample. If the card's performance is anywhere near that of the 4830, this is
an impressive feat.
|
System Power Consumption (AC) During Video Playback
|
|
Card
|
Rush Hour
(H.264)
|
Coral Reef
(WMV-HD)
|
Drag Race
(VC-1)
|
|
Asus EN9400GT 512MB
|
112W
|
110W
|
137W
|
|
PowerColor HD4650 512MB
|
102W
|
115W
|
137W
|
|
ATI HD 4670 512MB
|
94W
|
105W
|
129W
|
|
ATI HD 4770 512MB
|
132W
|
129W
|
148W
|
|
ATI HD 4830 512MB*
|
108W
|
134W
|
160W
|
|
Asus EN9800GT 512MB
|
119W
|
127W
|
141W
|
|
Diamond HD 4850 512MB
|
136W
|
151W
|
176W
|
|
* sample with unknown number of stream processors
|
Due to the HD 4770's high idle power consumption, video playback was not very
power efficient with our system using between 129W and 148W during playback. Only the HD 4850 drew more power on average.
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