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.
As expected, the heatsinks on these cards are more than up to the task of cooling down the core temperatures. It should also be mentioned that our samples were near-silent as they went about their jobs.
Power Consumption
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.
As we have seen in the past, both the HD 5850 and HD 5770 are leaders in the performance per watt category. The HD 5850 outperforms the GTX 285 on an almost embarrassing basis but is still able to consume significantly less power. On the flip side, there is the HD 5770 which is simply in another category altogether and shows the true meaning of efficiency against the competition from NVIDIA.