PowerColor Radeon HD 5850: Worth the Wait

Graphics Cards
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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
Asus GeForce 9400GT 512MB
11W
23W
PowerColor HD 4650 512MB
15W
28W
ATI HD 4830 512MB
18W
87W
PowerColor HD 5850 1GB
21W
132W
ATI HD 4770 512MB
28W
60W
Asus GTX 260 896MB
35W
145W
ATI HD 4870 1GB
67W
134W
HIS HD 4890 Turbo 1GB
71W
149W

We've criticized ATI in the past for the relatively high idle power consumption of their graphics cards when compared to Nvidia's offerings, but the HD 5000 series seems to have finally knocked out that particular problem. The HD 5850 uses about 21W when idle, a massive reduction compared to the HD 4890, impressively low for a high-end video card. ATI also managed a small reduction on load which is also admirable when you consider than its supposed to be 20~30% faster than the HD 4870/4890.

Video Playback

Test Results: Video Playback
Test State
Average
CPU Usage
Additional
DC Power*
Rush Hour
(1080p H.264)
5%
+25W
Coral Reef
(WMV-HD)
27%
+44W
Undead Battle
(720p x264)
4%
+22W
Spaceship
(1080p x264)
3%
+22W
*compared to idle

The HD 5850 passed our video playback test with flying colors, with H.264 and x264 playback adding only 25W and 22W respectively to DC system power, much of which can be attributed to the GPU as CPU usage was very low. Our WMV-HD clip required more CPU cycles and we noticed a bug: the core and memory clocks of the graphics card increased to the maximum 700/1025Mhz setting rather than the UVD speeds of 400/900MHz. As a result, the total system power draw increased by 44W, which is unusually high.



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