Power, temps, and further investigation
Idle power remains decent in CrossFire mode.
It's practically a Radeon HD 5970, and so is the under-load power-draw, evaluated at the mains and considered for the entire system.
Further examination
Examining the whole noise/heat/power issue in more detail and taking a real-world game into account, we played through Battlefield: Bad Company 2 and noted where system-wide power-draw was highest. The game works the CPU's cores and gives the GPU(s) a good going over. We then left the cards rendering the high power-draw scene for 10 minutes and logged the maximum temperature, fan-speed, and power-draw. The table, below, highlights our findings and provides a subjective analysis of the fan noise.
| GPU | Power-draw (maximum) | Temperature (maximum) |
Fan speed (maximum) |
Quietness /10 |
| GeForce GTX 470 | 354W | 94°C | 2,350rpm/3,290rpm | 5/3 |
| GeForce GTX 480 | 419W | 94°C | 2,720rpm/3,785rpm | 4/2 |
| Radeon HD 5850 XF | 371W | 83°C/73°C | 2,520rpm/1,980rpm | 4.5 |
| Radeon HD 5970 | 366W | 77°C | 2,460rpm | 5 |
| Radeon HD 5870 TOXIC | 324W | 66°C | 1,950rpm | 7 |
| Radeon HD 5870 | 288W | 76°C | 2,350rpm | 6 |
| Radeon HD 5850 | 260W | 63°C | 1,650rpm | 7 |
Let's explain the table. The noise perception is a subjective rating out of ten for the quietness of the card when under gaming load. Simple rpm don't always tell the full story. The Radeon HD 5870 TOXIC and single-GPU Radeon HD 5850 win out here, helped by the fan spinning relatively slowly due to low-ish temps.
There are two figures for the Radeon HD 5850 XF, and they relate to each GPU. The upper GPU is warmest due to the proximity of the second card. The combined noise is just a smidge louder than a single Radeon HD 5970 (we put this in directly afterwards to compare) but could be ameliorated if the cards were spaced out.
Tellingly, the two cards have a combined load which is some 50W less than a single GTX 480.
