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:
It is no wonder that the 3-way GeForce GTX 660 Ti SLI configuration needs the most power. Its system draws over 650 watts, which is 100 watts higher than the power consumption of the system with one GeForce GTX 690. Remarkably, the system with two GeForce GTX 660 Ti needs 155 watts more than the system with one such card whereas the third GTX 660 Ti only increases the power draw by 113 watts. This seems to indicate some inefficiency in the 3-way SLI design.
Our tests show that building a SLI configuration out of GeForce GTX 660 Ti is a viable solution. We’re talking about the 2-way SLI tandem in the first place as it showed excellent scalability in terms of average frame rate and was always ahead of the factory-overclocked GeForce GTX 680 from ASUS. However, if you want to build such a tandem, you must keep it in mind that the bottom speed may even be lower than that of the single card. But if you don’t mind losing something in terms of comfort in order to get a higher average performance, the GeForce GTX 660 Ti is going to be an interesting solution indeed.
As for joining three such cards in 3-way SLI mode, there are certain problems that must be noted. First, the scalability is lower by half compared to the tandem vs. the single card. Second, the minimal speed may be downright unplayable, like 10 or 12 frames per second. Third, the high power consumption and heat dissipation of this configuration call for a high-quality (and expensive) power supply and efficient cooling (perhaps even liquid cooling). If these downsides do not bother you, you can bravely build your 3-way GeForce GTX 660 Ti setup and enjoy high benchmarking results that even GeForce GTX 690 owners would be envious of.