Want to purchase a Radeon HD 5870, but can’t find one in stock? One alternative to consider is instead purchasing two Radeon HD 5770′s to take advantage of CrossFireX. Not only does this solution save you up to $80 at current pricing, but it proved in our results to offer even better performance in select titles, such as with Modern Warfare 2.
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 Windows desktop until things are completely idle. 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 30 minutes, which includes a one minute lull at the start, and a three minute lull at the end. After about 10 minutes, we begin to monitor our Kill-a-Watt to record the max wattage.
With the two cards pressed against each other, it’s no surprise to see the temperatures go so high – much higher than a single HD 5870. However, with OCCT, we see the worst possible effect of heat since it’s created to push graphics cards as high as possible. In testing for temperatures with real games, the temperature never went above 88°C, which when we’re dealing with numbers this high, is far better. As for power, the setup surprisingly only draws an additional 19W at full load, and 9W at idle. That’s not bad at all… I expected the difference to be much greater.