Results: Power, Temperature, and Overclocking
All of the cards are based on the 28 nm AMD GCN architecture. These cards also feature 2 x 6 pin power connections. This gives upwards of 225 watts of potential power draw, but at least with the 7800 series that number should be quite lower. The three cards all feature dual fan cooling designs that are more efficient than the reference cooling design.
In terms of power, all of the cards shake out in the same general area at idle. All of them share the power saving features that AMD implemented into the GCN architecture. In CrossFire, the second card is in fact totally powered down. This is why the single Hawk matches the CrossFire set at idle.
Once things get loaded up, we see some pretty fascinating results. It is not unexpected that we see such a jump when two 7870s are used, but what was unexpected was how much higher the Hawk was in power consumption than the larger, more powerful R7950. It is curious that the Hawk cannot outperform the R7950, but it pulls a lot more power. I think a big reason for this is the aggressive 1100 MHz overclock. TSMC’s 28 nm process is still relatively new, and improvements in both the process and the 7870 design might have an impact on future products when it comes to power draws at load.
The temperatures that these cards see are again quite interesting. At idle the Hawk has the lowest overall temperature, but at full load we see the R7950 take a pretty large lead. Even though that card is a Twin Frozr III design, it is a much larger heatsink with more fins than what is featured on the Hawk. The Hawk cards in CrossFire see around a 3 degree increase, but in a smaller case with not as much cooling, I would expect that number to be much higher.
The biggest issue I had with the Hawk was that of sound. At idle speeds and at partial load it was absolutely silent. Once things got loaded up though, it became surprisingly loud. It was easily heard outside of the closed case, and even across the room it was very obvious when the card spun up. I believe that MSI might have been a bit too aggressive in their fan speed profiles in this particular case. I would have rather seen a few degrees higher temperature with a lower volume while playing a game. Happily, users can adjust the fan profile with the Afterburner program. Users, if they are bothered by this sound, should take a good 15 to 20 minutes and test out the different settings and profiles that they can create. Yes, they will trade heat for sound, but as long as the board does not go above 85C they should be perfectly fine.
Using the Afterburner software, I did my best to push this card without totally burning it out. I raised the voltage to 1.2v and was able to get the core up to 1300 MHz. This is a 200 MHz increase from the stock speed, and an impressive 300 MHz above that of a stock HD 7870 GHz edition. The memory was able to go to 1450 MHz (5800 MHz effective) giving 185.6 GB/sec of bandwidth. To my thinking this is a very impressive overclock. The board did get a lot warmer, and the fan had to be run at full speed during testing. The card was very solid and fast at that speed.
To truly push this card, LN2 is needed. The user can then switch the BIOS and remove all of the protections built into the card. It would not surprise me if this card were to reach 2 GHz in such a situation. The GPU Reactor and Voltage points are all features that are aimed directly at this type of overclocking.