ATI HD3850 & HD3870: Improved Acoustics & Power Efficiency

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TEST RESULTS

#1 - Baseline, with Integrated Graphics: First, here are the results of our baseline results of the system with just its integrated graphics, without a discrete video card. We'll also need the power consumption reading during CPUBurn to estimate the actual power draw of each individual card later.

VGA Test Bed: Baseline Results
(no discrete graphics card installed)
System State
CPU Temp
System Power
AC
DC (Est.)
Idle
22°C
73W
Unknown
CPUBurn
39°C
144W
115W
Ambient temperature: 21°C, noise level: 20 dBA@1m

#2 - Radeon HD 3850: The fan was very loud at bootup, but it quickly throttled down to the point where it was below or at the ambient noise level of our test system. Oddly, we could not coax the fan to spin up again, whether automatically by stressing the GPU or toying with ATITool to do so manually. Still, the cooler surprised us by keeping the GPU core temperature at 89°C during extended load without artifacting or any other instability. Anything under 90°C is acceptable, and the fact that it was inaudible amazed us, especially since we were not impressed initially with the stock cooler design. Power consumption was very low, indicating excellent efficiency — there wasn't a lot of heat to dissipate.

VGA Test Bed: Radeon HD 3850
System State
GPU
Temp
CPU
Temp
System Power
AC
DC (Est.)
Idle
45°C
23°C
88W
66W
CPUBurn
51°C
41°C
157W
126W
CPUBurn + ATITool
89°C
42°C
208W
170W
Ambient temperature: 21°C, noise level: 20 dBA@1m

The fan problem may be specific to our test sample, as we know of many users who are successfully controlling the fan on their HD 3850s. Actually we don't even regard it as a problem, since cooling was fine at the speed the fan was stuck at.

#3 - Palit Radeon HD 3870: The fan control was automatic, but could also be over-ridden with ATITool. Setting the fan between 0% and 30% resulted in the same fan speed — what the card automatically used when idle. When stressed, the fan vacillated up and down between 30% and 50%, trying to keep the GPU temperature at around 90°C.

When we set the fan speed manually to stay at 30%, it was not enough to keep the card cool. Artifacts appeared in ATITool as the GPU temperature rocketed past 100°C. 40% seemed to be the sweet spot, keeping the GPU core at 90°C with only a small increase in measurable noise (22 dBA). Incidentally, 90°C is how well our X1950XTX VGA heatsink test card's stock cooler performs, but with the fan speed at 43% and a noise level of 28 dBA.

VGA Test Bed: Palit Radeon HD 3870
System State
Fan Speed
Noise Level
GPU
Temp
CPU
Temp
System Power
AC
DC (Est.)
Idle
30%
21 dBA
56°C
23°C
94W
71W
CPUBurn
30%
21 dBA
57°C
41°C
164W
132W
CPUBurn + ATITool
30%
21 dBA
102°C*
42°C
228W
187W
CPUBurn + ATITool
40%
22 dBA
90°C
42°C
228W
187W
CPUBurn + ATITool
50%
26 dBA
73°C
42°C
225W
184W
Ambient temperature: 20°C, noise level: 20 dBA@1m

The noise signature of the fan was poor. At 30% the overall noise level was low, but the fan had a slight ticking and a low-pitched hum. At 40% fan speed it registered 1dBA higher but the pitch of the sound also increased. At 50%, the ticking went away but the noise level became intolerable, thanks to higher air turbulence and the motor running like a small vacuum cleaner.

40% is the minimum we would run the fan at, but at that speed, its 22 dBA noise reading is deceptive as it's abrasive rather than smooth. It's too bad that ATI did not keep the heatpipe from the X1950XTX heatsink design or increased the size and area of the fins and employed a fan with better acoustical properties.



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