Besides morphological antialiasing introduced in the Radeon HD 68xx series, the Radeon HD 69xx series features Enhanced Quality AA. An additional mode for MSAA, you can enable it in the Catalyst control panel:
Its principle is illustrated by the next picture:
Besides two, four or eight samples, there is also the same number of interpolated points which require less GPU resources to process. The image quality improves while the performance hit is promised by AMD to be no higher than 10% compared to the ordinary antialiasing algorithm.
The Cayman also has a new power-saving technology. You can manage it from the Overdrive tab of the Catalyst control panel:
You can find a new slider here which is called Power Control Settings. You can set it in a range from -20 to +20%.
This setting changes the limit for the graphics card’s peak power consumption. You can set it low to save power or high to achieve better overclocking results. The Cayman has a few sensors keeping track of its status and load that help make the new GPU more energy efficient. When these sensors identify a test program like FurMark, a protection mode will be triggered, lowering the frequency of the GPU. This is how it works when you launch the Perlin Noise test from 3DMark Vantage:
It is clear that the GPU clock rate is changing depending on the current load, but the frame rate remains at the same level. We doubt that this power-saving mechanism is going to be that effective in other applications, though. There should be a performance hit, even though people from AMD say that there are but few such applications. Well, we’ll see.
To push the limit of this official frequency throttling higher, you just move the slider to the maximum of +20%. Here is how this changes the graphics card’s behavior in the Perlin Noise test:
You can also do the opposite thing. That is, you can lower the card’s peak power consumption by setting that option at a negative value. This leads to a performance hit but AMD says you won’t lose much speed even in this case.
The power adjustment range is written into the graphics card’s BIOS and we hope there will be tools to tweak it (to enable higher values, in the first place). This would prevent your overclocking attempts to be limited by the frequency throttling mechanism.
Summing up this theoretical part of our review, we want to show you a couple of slides that compare the performance of AMD’s Radeon HD 6950 and 6970 with Nvidia’s GeForce GTX 470 and 480, respectively.
AMD also notes that, like with the Radeon HD 68xx series, the efficiency of CrossFireX technology is higher with the Radeon HD 69xx cards.
We will surely check this out in an upcoming review. Right now, let’s take a look at the specifications and see what the reference Radeon HD 6950 and HD 6970 cards are like.