ASUS Republic of Gamers and X79 ROG Review – Rampage IV Gene, Formula and Extreme

A Byword About 4-way 7970 Scaling on X79

With three different benchmarks, we can say a little bit about the scaling on certain games when using almost the best consumer performance system put together - an X79 platform and several 7970 GPUs.  Numbers quoted here are whilst using the Rampage IV Extreme and i7-3960X at stock, and percentages are relevant to single card increases expected.

To start, Civilization V is not a good game to analyze for AMD.  In order to keep consistency with our previous testing, we had to use Catalyst 12.3 drivers, which are a few months old now.  As a result, with Civilization 5 we see no improvement on AMD moving from one card up to four, even at 2560x1440 and all the eye candy turned on.

Civilization V - One 7970: 78.73 FPS
Civilization V - Two 7970: 83.13 FPS (+5.6% of a single card)
Civilization V - Three 7970: 82.50 FPS (-0.1% of a single card)
Civilization V - Four 7970: 83.00 FPS (+0.1% of a single card)

If we look at Metro 2033, we know from previous experience that it is a tough benchmark.  It loves GPU power in all forms, and a system to back it up.  With the scaling, we observe that it tends to a limit, with a series of four cards giving just over double the single card performance.  Metro2033 is a perfect example of the law of diminishing returns, with the second card almost doubling performance, then the third card giving another ~40% of a card, and the final card giving another ~13%.

Metro 2033 - One 7970: 32.85 FPS
Metro 2033 - Two 7970: 61.63 FPS (+87.6% of a single card)
Metro 2033 - Three 7970: 74.59 FPS (+39.5% of a single card)
Metro 2033 - Four 7970: 78.90 FPS (+13.1% of a single card)

Dirt 3 is almost in a different league - this game seems to love GPU power and scales very well with it. Keep adding cards equals to an increase in FPS that is calculable (whether it is noticeable is up to the setup and users' eyes).  We see that each additional card adds ~60% or above the performance of a single card:

Dirt 3 - One 7970: 73.95 FPS
Dirt 3 - Two 7970: 136.28 FPS (+84.3% of a single card)
Dirt 3 - Three 7970: 195.11 FPS (+79.6% of a single card)
Dirt 3 - Four 7970: 237.40 FPS (+57.2% of a single card)

Ultimately, the scaling a user will experience is highly dependant on the game, the engine that game uses, and the drivers at hand.  If your main games are using the EGO 2.0 engine, then more cards seems like more performance!