Power Consumption (Idle and Gaming)

Putting a realistic, repeatable load on a GPU to get a decent idea of its real world power consumption and thermal output has long been something with which we've experimented here at bit-tech. We've found that synthetic benchmarks such as FurMark thrash the GPU constantly, which simply isn't reflective of how a GPU will be used when gaming.

It's such a hardcore test that any GPU under scrutiny is almost guaranteed to hit its thermal limit; the mark at which the card's firmware will kick in, speeding up the fan to keep the GPU within safe temperature limits. Conversely, simply leaving a game such as Crysis running at a certain point also isn't reflective of real-world use. There's no guarantee that the GPU is being pushed as hard as other titles might push it, and the load will vary between play-throughs.

We used to use the Canyon Flight test of 3DMark 06, as this was a punishing and repeatable test. However, we've now adopted Unigine's Heaven 3.0 benchmark, as its DirectX 11 features will stress all the parts of a modern GPU. We use the default settings and a resolution of 2,560 x 1,600. We then hit the Benchmark button and watch the power draw from the wall between the grass field scene and the second dragon scene - this is the toughest portion of the test for both Nvidia and AMD hardware.

We also have GPU-Z running in the background, and leave the Unigine benchmark running for ten minutes to record a peak GPU temperature. We present the temperature as a delta T (the difference between the temperature of the GPU and the ambient temperature in our labs).



Thermal Performance



*as there's no stock model of the HD 7850 2GB, it is not included in these graphs

Read our performance analysis.