Below each company's highest-end graphics cards, most offerings perform pretty similarly when it comes to power consumption. Nvidia's GeForce GTX 660 Ti really doesn’t have an advantage compared to the faster competition, except for the Radeon HD 7950’s high power consumption during Blu-ray playback.
Looking at the different interpretations of the GeForce GTX 660 Ti, Zotac's GeForce GTX 660 Ti AMP! Edition stands out with high GPU and memory clock speeds, and the Galaxy GeForce GTX 660 Ti GC 3 GB stands out for its extra memory. But neither exhibits dramatically different power use.
The consumption of two passively-cooler Radeon HD 7750s in CrossFire, operating at 1920x1080 with 8x MSAA is 98 W (102 W in Crysis 2). This is about 20 W less than Nvidia's GeForce GTX 660 Ti’s 118 W measurement (124 W in Crysis 2), and the GeForce was slower than the 7750s. The efficiency of Nvidia's GeForce GTX 660 Ti tanks once it's limited by memory bandwidth. Power consumption doesn't drop with frame rate. As a result, AMD's cards are as or more efficient at medium frame rates.
Real Clock Speeds under Full Load
We used the following graph earlier in this piece when were trying to explain why the different GeForce GTX 660 Tis didn't line up in the order we were expecting in 3DMark 11. Let’s take a closer look at where each card's thermal ceiling seems to be, and just how much GPU Boost acceleration the cards really get.
This is also interesting from a power consumption point of view. Our Asus GTX 660Ti DirectCU II simply stays at 915 MHz, which paints its thermal and acoustic performance into a different light since it's a lot easier to cool a card running 250 MHz slower.
MSI's N660 Ti PE 2GD5/OC shows particularly well. Zotac's GeForce GTX 660 Ti AMP! Edition, on the other hand, doesn't benefit from GPU Boost at all. Generally speaking, the cards on longer PCBs with an additional power phase are enjoying higher boosted clock rates than the ones using Nvidia's reference GeForce GTX 670 board.
Power Consumption Benchmarks in Different Scenarios