Temperature, Noise, Overclockability
We studied the power consumption of Barts-based solutions in our ASUS HD 6870 DirectCU review. Nonstandard variations of this graphics card can be much more voracious than the reference sample, especially if the user makes some changes to GPU voltage. An overclocked Radeon HD 6870 may need up to 150-160 watts in heavy 3D applications which is roughly equivalent to the power consumption of a non-overclocked GeForce GTX 560. As we found out earlier, these solutions are also comparable in terms performance at such settings.
Now, both graphics cards we are discussing in this review have nonstandard coolers with massive heatsinks and high-performance fans. The MSI card has even two fans, but do they give it any advantage in terms of cooling?
Well, the MSI R6870 Hawk is indeed better than the PowerColor HD6870 PCS+ in 3D applications by as much as 14°C. The ambient temperature being 24-25°C during this test, the card's 62°C under load is an excellent result. Its 32°C in idle mode also seems to be a record-breaking result. On the other hand, the PowerColor cools its GPU quite effectively, too. Its cooler is more efficient than AMD's reference one, especially considering that the PowerColor card is pre-overclocked.
Now let’s check out how much noise the two graphics cards produce, the level of background noise being 38 dBA during this test:
The PowerColor HD6870 PCS+ fails here completely. We don’t know if this is the behavior of our specific sample of the card or the developer deliberately achieved the high cooling performance at the expense of acoustic comfort, but the fan management system is set up very aggressively and quickly accelerates to 73% of the fan’s full speed in 3D mode, making the card very noisy. It is also noisy in idle mode although the fan speed lowers to 21%. Judging by the spectrum of the noise, the fan is not defective. It is just naturally noisy when spinning at high speeds. We hope the fans of off-the-shelf samples of the HD6870 PCS+ will be set up less aggressively.
The MSI R6870 Hawk performs much better here. The large heatsink and the couple of fans do their job well and quietly. The level of noise remains within comfortable limits even at heavy loads when you use the Silent mode although the card is somewhat noisier than the ASUS HD 6870 DirectCU we reviewed earlier. The fan speed rises from 40 to 56% of the maximum then. When not running heavy 3D applications, the Hawk was completely inaudible among the rest of the system components. Thus, you don't really need to switch the fans into the Performance mode.
MSI wins in terms of cooling, but what about overclocking?
We had expected the MSI card to be better in this respect, too. Indeed, the PowerColor HD6870 PCS+ could not even notch 1000 MHz in terms of GPU clock rate despite our increasing its GPU voltage. The MSI R6870 Hawk, on its part, could get as high as 1065 MHz at a GPU voltage of 1.25 volts.
The MSI is also better in terms of memory overclocking yet we are going benchmark both cards at the highest frequencies they achieved.