Power And Temperature
Power consumption is measured at the system level, and we're using Metro: Last Light as our workload to gauge peak draw.
I zeroed this chart out at 45 W, which is roughly where the system idles when we don't have a graphics card installed. This gives us a more visual representation of each card's power consumption relative to the rest of the field.
There's a 29 W difference between the top and bottom boards under load. As we expected, the Radeon HD 7750 is the most power-hungry entry. We're also a little surprised to see the GeForce GT 630 GDDR5 following just 5 W behind. The DDR3-equipped Radeons use the least amount of power, and the new 7730s pull more from the wall than their predecessors, despite a lower TDP specification.
When it comes to thermal performance, cooling solutions have a big impact. So, I've included manufacturer names in the above chart to indicate cards with non-reference heat sinks and fans.
I zeroed out the chart at our lab's ambient temperature of 24 degrees Celsius. Although Gigabyte's Radeon HD 6670 with DDR3 posts the lowest GPU temperature under load, Sapphire's Radeon HD 7730 cards perform well in this comparison, too.