|by Michael "SKYMTL" Hoenig | September 22, 2009|
Heat & Acoustics / Power Consumption
Heat & Acoustics
For all temperature testing, the cards were placed on an open test bench with a single 120mm 1200RPM fan placed ~8” away from the heatsink. The ambient temperature was kept at a constant 22°C (+/- 0.5°C). If the ambient temperatures rose above 23°C at any time throughout the test, all benchmarking was stopped. For this test we use the 3DMark Batch Size test at it highest triangle count with 4xAA and 16xAF enabled and looped it for one hour to determine the peak load temperature as measured by GPU-Z.
For Idle tests, we let the system idle at the Vista desktop for 15 minutes and recorded the peak temperature.
The temperatures we saw weren’t exactly earth-shattering but they were particularly good when compared to other ATI cards from the last generation. What was even more impressive was the fact that unlike every high performance reference ATI product we can remember, the HD 5870 is dead quiet. It isn’t silent per se but you would be hard pressed to find a quieter fan on a reference GPU. This coupled with good temperatures is a testament to the low heat output of the core.
For this test we hooked up our power supply to a UPM power meter that will log the power consumption of the whole system twice every second. In order to stress the GPU as much as possible we once again use the Batch Render test in 3DMark06 and let it run for 30 minutes to determine the peak power consumption while letting the card sit at a stable Windows desktop for 30 minutes to determine the peak idle power consumption. We have also included several other tests as well.
Please note that after extensive testing, we have found that simply plugging in a power meter to a wall outlet or UPS will NOT give you accurate power consumption numbers due to slight changes in the input voltage. Thus we use a Tripp-Lite 1800W line conditioner between the 120V outlet and the power meter.
Yes, we were shocked by these power consumption numbers as well. More like gobsmacked actually. The 40nm manufacturing process along with second generation GDDR5 which boasts higher efficiency means the HD 5870 was extremely power efficient during this review even though it wipes the floor performance-wise with nearly every other product. We are looking at near HD 4870X2 performance with GTX 285 power consumption.
It looks like ATI’s active clock gating is also working considering the idle efficiency hovers around that of a GTS 250 512MB which wasn’t included in the chart...yes, a GTS 250. Need we say more?
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