In the fourth-generation Core processors, known under the code name Haswell, Intel has implemented a number of new developments that aim at reducing CPU power consumption in sleep mode. Thus, the new state of deep sleep, called C7, can reduce processor power consumption current of 0.05 A (0.6 W). In this state, other devices that operate from the bus +12 V, can go to the minimum energy consumption, if not shut down. This mode significantly reduces power consumption. However, in combination with the load on the +3.3 V and +5 V specified mode may cause some disruption in power supply units.
Fractal Design Company reported about its power supplies that are compatible with processors Haswell. According to the manufacturer, are fully compatible with the new model series processors Newton R3 and Tesla R2, and the model series Integra R2 labeled as supposedly compatible.
The power supply series Newton R3 and Tesla R2 Tyre +3.3 V and +5 V use conversion DC-DC. All blocks using this conversion method capable of providing full operation +3.3 V and +5 V, even in the absence of load on the +12 V. This means that they support the new mode C7.
As for the power supply Integra R2, they use a method of group to stabilize the bus +3.3 V and +5 V, which means greater volatility of the difference voltage load on these bus and +12 V. As for now, Intel has not yet released guidance and methodology for testing systems based on the new platform and objective criteria for compliance with Haswell yet, the manufacturer conducted independent testing of power supplies series Integra R2. According to Fractal Design, modern power supplies, which use a group stabilization, much more stable solutions, released a few years ago, so that blocks of R2 can provide the voltage according to the ATX standard for all levels of line loading +3.3 V and +5 V during sleep state.