Power consumption, temperatures and noise
The Sapphire HD 5970 TOXIC's ability to lower core and memory frequencies when idling to as little as 157MHz and 1,200MHz, respectively, is to thank for the reasonable system-wide idle power draw.
Crank up the load, and the system equipped with the HD 5970 TOXIC soars close to 700W. We're not entirely certain why the card is significantly more power hungry than a regular Radeon HD 5970, but it's worth noting that our test is conducted using a 10-minute stretch of FurMark - an intensive benchmark that puts close to 100 per cent load on both GPU cores.
Consider the loaded results as a worst-case scenario. Users are unlikely to see similar figures during real-world usage, and we'll touch on that further down the page.
That's the sign of a very, very impressive cooler. At idle, Sapphire's Radeon HD 5970 TOXIC 4GB - the fastest single card in our line up - also happens to be the coolest.
Sapphire's choice of cooling solution does a remarkable job under load, too, keeping the card a few degrees cooler than AMD's reference design - despite the superior frequencies and larger frame buffer.
The pedant in us reckons all GPUs - even at the ultra-high-end - should run significantly cooler than what we've become accustomed too, but Sapphire's card looks impressive when compared to the competition.
A real-world assessment
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 card rendering the high power-draw scene for 10 minutes and logged the maximum temperature, fan-speed, and power-draw.
The observations were noted with the card(s) installed inside a Corsair Obsidian 800D chassis with side panels on. The 'upper' (hotter) card's temperature and fan-speed are noted if we're evaluating a multi-GPU setup. 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 (higher is better) |
|---|---|---|---|---|
| Radeon HD 5970 TOXIC 4GB | 488W | 64°C | 2,090rpm | 6.5 |
| Radeon HD 5970 2GB | 366W | 77°C | 2,460rpm | 5 |
| Radeon HD 5870 XF 1GB | 435W | 84°C | 2,700rpm | 4.5 |
| Radeon HD 5850 XF 1GB | 371W | 83°C | 2,520rpm | 4.5 |
| Radeon HD 5870 TOXIC 2GB | 324W | 66°C | 1,950rpm | 7 |
| Radeon HD 5870 1GB | 288W | 76°C | 2,350rpm | 6 |
| Radeon HD 5850 1GB | 260W | 63°C | 1,650rpm | 7 |
| GeForce GTX 470 SLI 1.2GB | 532W | 94°C/86°C | 2,650rpm/3,500rpm | 3.5/2 |
| GeForce GTX 480 1.5GB | 419W | 94°C | 2,720rpm/3,785rpm | 4/2 |
| GeForce GTX 470 1.2GB | 354W | 94°C | 2,350rpm/3,290rpm | 5/3 |
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 doesn't always tell the full story.
During our session of Battlefield: Bad Company 2, Sapphire's card rose to just 64°C and was able to keep fan speeds a fraction over 2,000rpm. Highly-intensive tests such as Furmark will cause the fan speeds to rise in excess of 2,500rpm - at which point the cooler becomes noisy - but such speeds are unlikely to be a regular occurrence when gaming.
Showing the advantages of running a single card, the HD 5970 TOXIC 4GB is quieter and cooler than the ultra-high-end competition. It doesn't win out in all areas, though, as its 488W in-game power draw is a little on the high side.
