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AMD's Radeon HD 5000-Series: Measuring Power Efficiency

Benchmark Results: Crysis, The Classic Approach

Even after all these years, this game still proves to be one of the most graphically-intensive benchmarks out there. Due to this fact, we figure it should make a good example how games and graphics benchmarks apply load to the GPU. Below, you can see the relationship between GPU utilization, temperature, and system power consumption.

These measurements are taken at 1024x768 with the High quality preset using AMD’s Radeon HD 4670. Even at such a low resolution, sustained GPU utilization is very close to, if not pegged at 100%. From experience, the difference in power consumption between Crysis and FurMark is about 10 W at full load using this setup. This behavior is what we expected with these graphics cards under load. Let's see how all the cards line up.

Based on gameplay and testing experiences, you'll want at least 40 frames per second to play Crysis smoothly on all levels. However, 40 FPS is a minimum. On occasion, you'll still see drops below 30 FPS in the Assault and Redemption levels. If you want a more enjoyable experience with no sudden drops below 30 frames, set the bar at 55 FPS.

The results show that AMD’s Radeon HD 5670 offers roughly the same frame rates as its Radeon 2900 XT, but with much lower power consumption (almost half of the older card, actually). The faster Radeon HD 5770 delivers higher frame rates, but you'll use 50 W more than the HD 5670.

These two cards add about 40 to 100 W to the base system’s consumption numbers. We're CPU-limited with both Radeon HD 5870 cards, as the pair provides frame rates above 50 FPS, even at 1920x1080.

If we compare the numbers, this is what we get.

Radeon 2900 XTRadeon HD 5670Radeon HD 5770Radeon HD 5870 1 GBRadeon HD 5870 2 GB
FPS (1920x1080)2122375454
Power (minus base system power consumption)18744104159209

The best performance per watt ratio goes to the Radeon HD 5670. But if you look at the frame rates, you'd likely will have to use 1024x768 or below (or use a slightly lower preset) to make the card playable. The Radeon HD 5770 offers good enough performance to make 1280x720 viable. 

Now, if you look at the 1 GB Radeon HD 5870 compared to the Radeon HD 5770, you can see the difference is not that large. With a higher-performing processor, frame rates would likely scale well enough to tip the scales in the faster card’s favor. For instance, a 70 FPS result would mean the Radeon HD 5870’s FPS/watt would go up to .45, which is very close to the Radeon HD 5670.