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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 system power under CPUBurn with just the integrated graphics
is subtracted from the system power under CPUBurn with the add-on card, we obtain
the increase in idle power of the add-on card. (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 ATITool
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 ATITool
should not skew the results, since the CPU was running at full load in both
systems
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Power Consumption Comparison (DC)
|
|
Card
|
Est. Power (Idle)
|
Est. Power (ATITool)
|
Est. Power (FurMark)
|
|
ATI HD 4670
|
3W
|
38W
|
40W
|
|
ATI HD 3850
|
11W
|
55W
|
N/A
|
|
Asus EN9600GT
Silent
|
26W
|
65W
|
N/A
|
|
Palit HD 3870
|
17W
|
72W
|
N/A
|
|
Asus EN9800GT
Matrix
|
32W
|
72W
|
80W
|
|
ATI HD 4830*
|
18W
|
80W
|
87W
|
|
Diamond HD 4850
|
50W
|
101W
|
N/A
|
|
Asus ENGTX260
|
35W
|
122W
|
N/A
|
|
* We were unable to determine the number of stream
processors enabled on our HD 4830 production sample. Power consumption
may be higher on retail units.
|
We estimate the power draw of the EN9800GT Matrix to be approximately 32W during
idle, 72W with ATITool running, and 80W with Furmark. On load it is quite similar
to the HD 3870, but
with much higher idle power consumption. It is also incrementally more power
hungry the EN9600GT
though if its power management software had been operational, it may have done
better in this regard. For a midrange card, these numbers are more or less the
norm.
The key Asus software provided with the card, iTracker (for controlling fan
speed and monitoring temperatures) and Super Hybrid Engine (dynamic voltage
/ frequency control) froze up on our test system when we attempted to load them.
We tried different versions of the software along with various driver sets to
no avail. We were therefore unable to test Asus' Super Hybrid Engine power saving
ability. Whatever power management there was occurred at the driver level, not
in software. Without the advantage of Super Hybrid Engine, we can assume that
the performance our test sample is typical of other 9800GT's. This accords with
other reviews around the web: A modest increase in idle power consumption over
the 9600GT is about right for a reference design 9800GT.
Video Playback
|
Video Playback Results: EN9800GT
|
|
Video Clip
|
Mean CPU Usage
|
Peak CPU Usage
|
AC Power
|
|
Rush Hour
|
3%
|
9%
|
~119W
|
|
Coral Reef
|
18%
|
29%
|
~127W
|
|
Flight Sim.
|
31%
|
46%
|
~138W
|
|
Drag Race
|
34%
|
47%
|
~141W
|
The EN9800GT handled our video playback testbed with ease. CPU usage during
playback fairly low except for our more demanding VC-1 clips.
|
Video Playback Comparison
|
|
Video Clip
|
HD 3870
|
EN9600GT
|
EN9800GT
|
|
Mean
CPU
|
AC
Power
|
Mean
CPU
|
AC
Power
|
Mean CPU
|
AC
Power
|
|
Rush Hour
|
3%
|
~105W
|
2%
|
~113W
|
3%
|
~119W
|
|
Coral Reef
|
27%
|
~118W
|
15%
|
~121W
|
18%
|
~127W
|
|
Flight Sim.
|
50%
|
~130W
|
28%
|
~131W
|
31%
|
~138W
|
Compared to two cards with similar power draws, the EN9800GT Matrix proves
to be a bit inefficient for video playback alone. Its higher idle power consumption
carries over to video playback when neither the CPU or GPU is under stress.
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