By most definitions, AMD’s Radeon HD 6900 graphics cards are powerful, but for those who are looking to push huge resolutions, a little more oomph might be desired. That’s where multi-GPU configurations come in, and to see what AMD’s latest are capable of, we’ve tested out both the HD 6950 and HD 6970 in CrossFireX.
Power & Temperatures
To test our graphics cards for both temperatures and power consumption, we utilize OCCT for the stress-testing, GPU-Z for the temperature monitoring, and a Kill-a-Watt for power monitoring. The Kill-a-Watt is plugged into its own socket, with only the PC connect to it.
As per our guidelines when benchmarking with Windows, when the room temperature is stable (and reasonable), the test machine is boot up and left to sit at the desktop until things are completely idle. Because we are running such a highly optimized PC, this normally takes one or two minutes. Once things are good to go, the idle wattage is noted, GPU-Z is started up to begin monitoring card temperatures, and OCCT is set up to begin stress-testing.
To push the cards we test to their absolute limit, we use OCCT in full-screen 2560×1600 mode, and allow it to run for 15 minutes, which includes a one minute lull at the start, and a four minute lull at the end. After about 5 minutes, we begin to monitor our Kill-a-Watt to record the max wattage.
Note: Due to power-related changes AMD has made to its HD 6900 series, and NVIDIA to its GTX 500 series, we cannot run OCCT for the sake of stress-testing. As a result, we have opted to use 3DMark Vantage’s Test 2 (space flight) to get some metrics until we’re able to re-test the entire suite with the updated method.
Temperatures in CrossFireX weren’t too extreme, which is nice to see. But, one thing I don’t record here is audio, and I can honestly say, when the cards are being stressed, you will hear their fans if you’re not using headphones or loud speakers. Water-cooling or perhaps even custom coolers would remedy this, but that’s not the simplest option for most.
On the power side, we managed to break through the 600W mark on the HD 6970s, so as mentioned on the front page, an 800W power supply is heartily recommended to run that, or the HD 6950 configuration.