Thermal testing was conducted by monitoring the various GPU temperatures with HWMonitor 1.14 64-Bit
. The idle condition was established by recording the temperature after letting the system sit for 30 minutes with only HWMonitor launched. The load condition was established by running 3DMark Vantage two times back-to-back, followed by two back-to-back sessions of the Resident Evil 5 benchmark. HWMonitor is capable of logging current, minimum, and maximum temperature, so once all testing was completed, the maximum temperature was recorded. All testing was completed on an open testbed with relatively still air in a room with an ambient temperature of 20C.
What we have is an incredibly cool running GPU that doesn't need to make a whole lot of noise to stay that way. As mentioned earlier, the cooling fan never got loud, and seeing how cool it can stay at the same time was very impressive. Even in CrossFire mode, the GPU sandwiched between the two PCBs didn't get hot. The temperature shown above is for that GPU, and the 'lower' GPU was at just 63C at the same time.
Power Consumption Testing:
Power consumption testing involved the use of an AC power monitor, the Seasonic Power Angel, to keep track of the AC Wattage drawn by the test system. Since all hardware other than the video card remained the same from test to test, any change in the Wattage would be due to the demand of the graphics card. Idle conditions were established by letting the system sit at the Windows desktop until a stable reading was achieved, and for load testing 3DMark Vantage was executed two times back-to-back. Peak values were recorded from the Power Angel's display and recorded in the chart below.
The results here are very impressive. Idle board power is advertised as just 18W, and while this test can't apply an exact number, it does confirm that it doesn't draw much. Even adding a second card in CrossFire only bumps things up 13W. Under a load, the CrossFire combination uses 50W less than a single HD4890 card, and as we saw they can easily hang with that high performance card in most games / tests.