SLI With GeForce GTX 280 Superclocked
If you thought the GeForce GTX 280 would suffer the same temperature problems in SLI as the GTX 260 in SLI mode, then you’d be mistaken. However, the powerful two-card solution encounters other problems. For instance, maximum power consumption is 540 watts, but both overclocked cards should fallen between 640 and 710 watts with the test system. The lower power consumption in SLI mode means that the temperature and noise level is lower than for a single card.
Thermal throttling of the graphics chip (as seen on the GTX 260) is not the reason why the GTX 280 in SLI only hits 85 degrees. A defect is also not likely, as the frame rates are slightly higher than the level of the Geforce GTX 260 in SLI. And both GTX 280 cards function normally when they’re running on their own. The loss of performance can only be explained by the lack of CPU horsepower to help facilitate scaling, which can be clearly seen from our overclocking results.
Although both GTX models are overclocked from the factory, the overall evaluation shows a loss of performance. If you average all the games of the benchmark suite, the overclocked GTX 280 in SLI saw a drop in performance of 1.1%, whereas the single card has a 5.8% increase. In Mass Effect (UT3 Engine), the single card at 1920x1200 pixels—with anti-aliasing—achieved an increase in frame rate of around 16%. In SLI mode, it decreased 0.8%.
Here are some highlights: World in Conflict at 1920x1200 pixels with 4xAA achieved 32.8 fps on a single card. With GTX 280 in SLI it hit 45.6 fps (the MSI overclock produced 44.2 fps). Mass Effect at 1920x1200 pixels with 8xAA and a single card reached 60.6 fps, and with the GTX 280 in SLI hit 74.6 fps (the MSI overclock was at 74.0 fps).
As you can see, SLI adds an acceptable level of additional power at the right resolutions, but without the platform to back that configuration up, you’ll actually sacrifice performance. If you look at the individual benchmarks, the worst values come from low resolutions and badly optimized games, which react negatively to SLI if they react at all. An important factor is now also the CPU—with more power, higher frame rates should be possible, and MSI’s factory overclocking should also provide additional gains. But without a powerful processor it is better to stick to a single card for 3D games, as the GTX 280 in SLI requires a little more in the way of system performance.
In 2D mode, the power consumption is 203 watts, while in 3D mode the pair draws 540 watts (from the wall). The GTX 260 in SLI drew 610 watts. According to the manufacturer’s specifications, both 3D cards should lie between 640 and 710 watts with the test system. If you wish to operate the overclocked GTX 280 in SLI mode, you will need a branded power supply with between 530 and 570 watts and 44 to 48 A on the 12 volt rail for a standard system. If the entire system reaches the top value of 710 watts (from the wall) a branded power supply with between 600 and 650 watts on that rail should be sufficient.
