We measured the power consumption of computer systems with different graphics cards using a multifunctional panel Zalman ZM-MFC3 which can report how much power a computer (the monitor not included) draws from a wall socket. There were two test modes: 2D (editing documents in Microsoft Word and web surfing) and 3D (the benchmark from Metro 2033: The Last Refuge at 2560x1440 with maximum settings). Here are the results:
As opposed to the performance tests, the power consumption of the systems with one, two and three GeForce GTX 670s increases linearly, in steps of 175 watts. This is roughly equal to the specified power draw of the GTX 670 (170 watts). You’ll need an 850-watt or higher PSU for a configuration with an overclocked six-core CPU and three overclocked GeForce GTX 670s.
We can also note that the single GeForce GTX 670 and GTX 680 consume 20 watts less with the new driver (compared to our previous tests on the same testbed), just as promised by Nvidia. Thus, the system with a single GeForce GTX 680 needs 100 watts less at high load than the system with an AMD Radeon HD 7970 GHz Edition. We are yet to test an actual HD 7970 GHz Edition, so these are not final results.
Our tests of SLI configurations built out of overclocked GeForce GTX 670s suggest that a 2-way tandem can significantly boost performance in most games, especially in heavy ones and at high resolutions. A 3-way SLI is a different story because the third card doesn’t provide significant performance benefits, except for a couple of games, whereas this trio has more problems with the bottom speed than the tandem. We can blame a lot of factors for that. We used graphics cards from different brands, our mainboard doesn’t support three PCIe 3.0 slots at x16 speed (but there are actually no such LGA2011 mainboards at all), our platform may not have been fast enough to match the 3-way SLI configuration, or the GeForce driver may be not yet polished off.
That said, we guess multi-GPU configurations are just prone to have such problems. It’s not easy to make them show their theoretical best as there are too many factors to take care of when building them. And we haven’t even mentioned the high noise and cooling-related problems unavoidable with three GeForce GTX 670s. So, graphics subsystems with three or more graphics cards are largely meant for testers who want to set new performance records. For ordinary gamers who want maximum performance regardless of its cost, we’d recommend one or two GeForce GTX 690s. We had only one problem with the GTX 690s in SLI mode – our platform was too slow to keep up. We’ll discuss this topic in more detail in an upcoming review, though.
We also want to add a few words about the results of the Zotac GeForce GTX 670 2GB AMP! Edition. Thanks to its factory overclocking, this card is as fast as the top-end GeForce GTX 680 although costs about 20% less. Coupled with the GTX 680 PCB, efficient cooler and extended 5-year warranty, the Zotac GeForce GTX 670 AMP! Edition seems to be one of the most attractive GTX 670s available today. It is going to be a perfect choice if you’re shopping for a GTX 670 right now.
And as a final remark, we don’t think that today’s competition between the Nvidia GeForce GTX 680 and the new AMD Radeon HD 7970 GHz Edition is conclusive. We’ll test them again with the newest drivers when we get a reference sample of the AMD card.