Fractal Design appears to have optimized the Integra R2 750W for very high efficiency at low loads, as the power supply displayed amazing (87.2% with 230VAC) efficiency at 20% load for an 80Plus Bronze certified product. However, the efficiency of the power supply diminishes rapidly when it is heavily loaded, forbidding it from achieving a better 80Plus certification.
The Integra R2 750W is not a quiet power supply but it actually performs very well for an 80Plus Bronze certified power supply with such a small chassis and high power output. Noise levels are very low up to 40% load, with the unit being essentially silent. Between 40% and 60% load, the fan is audible but volume levels remain low, comfortable for everyday use. If a load of 400W or greater is placed on the unit, the fan will accelerate quickly, reaching clearly audible levels from a meter away.
The thermal performance of the Integra R2 750W was expected, all things considered. The 80Plus Bronze certified unit has a linear, steady thermal performance, with a temperature delta of 4.5 degrees Celsius at minimum load and 8.4 degrees Celsius at maximum load.