Power Consumption & Temperatures
Despite the potentially enormous power consumption of the R9 295X2, it's a sleeper at idle, consuming just 10 watts more than the R9 290X. It was also slightly more fuel efficient at idle than a pair of GTX 780 SLI cards.
When playing Crysis 3, the R9 295X2 takes the system power consumption to 566 watts, 13% more than the older HD 7990. This was also 16% more power than consumed by the GTX 780 SLI system and 86% more than a single R9 290X.
In Max Payne 3, the R9 295X2 peaked at 505 watts making it the only system configuration to break the 500w barrier in this game, pulling 18% more power than the GTX 780 SLI cards and 63% more than a single R9 290X.
Sleeping Dogs pushed the R9 295X2's system consumption to nearly 600 watts, 18% more than the GTX 780 SLI cards and 69% more than the R9 290X.
Temperatures
In the past, we have used FurMark to measure maximum operating temperatures but we are in the process of changing testing methods. For now, we are going to measure operating temperatures with the three games in which we test power consumption.
In all three games, we reached a maximum operating temperature of just 62 degrees. Even after an hour of playing Crysis 3, the temperature never exceeded 62 degrees and both GPUs remained locked at 1018MHz with near 100% utilization on both for most of that time.
As impractical as the closed-loop system might be, it has proven to be the perfect solution for these extreme dual-GPU graphics cards.