When single card can’t satisfy enthusiastic players’ need to pursuit high performance, multi-GPU setup naturally becomes the ultimate equipment of high-end players. Theoretically, the efficiency of multi-GPU configuration is supposed to be like 1+1=2, 1+1+1=3 or 1+1+1+1=4. In fact, due to some factors, the performance outcome is another case.
For instance, since DX11 era, the CrossFire efficiency of HD 5800 and HD 6800 series is improving at a stable pace. Last year we have done two test on HD 6850 CrossFire. In the first test, dual-GPU efficiency was only 68%, while in the second test, the average CrossFire efficiency of dual-HD 6850 was over 84% thanks to driver optimization.
This time AMD has announced its new-generation HD 7970 graphics card which topping single-GPU performance, what about its CrossFire efficiency? Any surprise? Would like to get the answer? just follow our test.
The test bed included Intel Core i7-3960X CPU (3.3GHz-3.9GHz), G.Skill quad-channel Ripjaws DDR3 1600 9-9-9-24 memory (16GB), Gigabyte G1 Assassin2 X79 motherboard, and Prolimatech Super Mega+12cm x2 fan. It was conducted under Win7 X64 OS, and we installed the latest driver AMD was designed for HD 7970, and latest CrossFire configuration file in the AMD’s official website.
CrossFire Efficiency Boost
(Notice: The scores with italic part was not calculated in average CrossFire efficiency.)
From the test result, we could know dual-HD 7970 CrossFire efficiency was quite surprising, most of items was over 80%-90%, the efficiency with some of the items (like 3DMark 11 Xtreme mode, FarCry2, H.A.W.X, Battlefield 3 and LuxMark) were even close to 100%. In addition, the CrossFire efficiency was much higher under higher resolution and image setting. Take 3DMark 11 Performance mode as an example, the GPU performance achieved 101%, which was close to the theoretical value.
The CrossFire efficiency which was below 70% mostly came with DX9 gaming. At this time, the main system’s main bottleneck didn’t lie in graphics, whole performance has limited improvement in CrossFire efficiency. It only featured 55% improvement in Street Fighter 4, 15% with Modern Warfare 3, while no improvement in Elder Scrolls; Skyrim, the CrossFire was invalid in spite that we installed AMD’s CrossFire configuration file, the same case was in ComputeMark test item.
In Batman: Arkham City, the performance even decreased, which was 20% lower than single graphics. It must have something to do with driver optimization, we had to wait for the update.
From the current test result, CrossFire efficiency of HD 7970 are highly expected, it will be not a difficult thing to realize over 90% or close to 100% efficiency. Surely, the existing driver needs to be optimized, there comes with some minor issue in our test. For example, in single card test, Battlefield 3 could enable with fraps at the same time, but in CrossFire setting, the game would be black screen if we first enabled fraps. In addition, in Crysis 2 test, sometimes it would restart suddenly, and then lowed to single-GPU mode. However, HD 7970′s CrossFire efficiency would be more amazing in the wake of optimized driver.
Decent power consumption control
Apart from CrossFire efficiency, another issue was the power consumption that we would pay much attention to. We chose five states: idle, 3DMark 11 Xtreme mode (graphics 4 cycling), Modern Warfare 3, Battlefield 3 and Furmark loading, we recorded the maximum power consumption in the five states.
The idle power consumption of single-GPU was 83W, while only with 87W in dual-GPU CrossFire test thanks to ZeroCore super-low idle power. In 3DMark 11, the power consumption was only 291W, basically consistent with 289W in single-GPU. The dual-GPU power consumption hiked from 331W to 471W, improving by 140W in Modern Warfare 3. While in Battlefield 3, the power consumption promoted from 336W to 569W, increasing by 233W. And in loading test, power consumption surged from 435W to 676W, about 241W higher than single-GPU setting.
The excellent performance was related with AMD graphics’ advanced power consumption control technology. 3DMark 11′s recycling test only let one graphics card be in full-load state, while another in idle state, the overall power consumption between them was not in a large gap. In addition, the single-GPU power consumption of Modern Warfare 3 and Battlefield 3 featured a minor gap, but in dual-GPU setting, Battlefield 3 had an obvious performance improvement than Modern Warfare 3, suggesting high-participation of two graphics cards, dual-GPU setting’s power consumption gap was naturally much higher than that of single-GPU. For the same reason, the case was the same with Furmark loading, at which time two graphics cards was in 100% full-speed operation, featuring the biggest power
(Click to enlarge)
In 3DMark 11′s graphics 4 recycling test, only one graphics card was in full-load state, while another in idle state.
Two graphics card in full-loading state (Click to enlarge)
In summation, the CrossFire efficiency of HD 7970 is pretty high, it’s fine to hold efficiency of 80%-90% in most of the test and games, especially in demanding DX10/DX11 gamings, 90%-100% efficiency is common to be seen, at the same time dual-card power consumption performance is quite satisfactory, in light loading condition, the gap between single-GPU and dual-GPU system is small, of course, in high-loading state, the gap would be over 200W, but there features evident performance improvement, for enthusiastic players it’s a worthy thing.
The driver we used in our current test is just the beta version, it doesn’t have a good CrossFire support in a few games due to some bugs, however, it’s understandable as the graphics has just launched, it needs some time for the matched driver to be optimized. According to our previous experience, we could only get relative perfect driver after at least 2-3 times of driver optimization, so at present let most games enjoy high CrossFire efficiency of HD 7970.