Power Consumption: General-Purpose Computing
GPGPU Endurance Test
In order to create a consistent load that mimics something you might do in the real world (and doesn't get categorized as a "power virus" by the driver), I fired up one instance of GUIMiner per GPU, creating a 100% load.
The Radeon R9 295X2 draws a little more power here than the gaming test on the previous page, but amazingly doesn't exceed 450 W. PowerTune steps in, as you can see in the chart below, and the dual-GPU card's performance drops compared to the single-processor boards. You could try pushing the Radeon R9 295X2 above 500 W by increasing its power target, but it really wouldn't make any sense to do so.
The Radeon R9 295X2 draws a total of 420 W from the auxiliary power connectors, and only a few watts more from the motherboard's PCI Express slot.
In comparison, the two-generation-old Radeon HD 6990 pulls about 360 W from the auxiliary connectors, but averages a more substantial 62 W from the motherboard's slot, with peaks up to 74 W.
Finally, the Radeon HD 7990 is forced to hit the brakes due to a lower peak clock rate under heavy load.