Be Quiet! announced in a press release that all of its current power supplies support the new low power states of Intel's Haswell processor:
Be Quiet!, market leader with power supplies in Germany for seven consecutive years, confirms that all of it's current PSU models support Intel's fourth generation of Core processors (Codename Haswell). Intel's upcoming Haswell CPUs impose stricter requirements on the power supply regarding energy saving features. To lower the power consumption of current computers even more, the new processors feature new sleep states called C6 and C7. In these states, the processor is nearly shut off completely, bringing down the power consumption close to zero.
Saving money risking quality
If consumers can use this new deep sleep state depends on their power supply. It must run under very low loads below 0.05 Amps. Many inferior power supplies have problems in these low load situations. Low quality components might even lead to the activation of the PSUs safety circuits. In that case the computer would not start again.
be quiet! is Haswell ready
As for be quiet!, all current power supply series, starting with the entry-level Pure Power L8 up to the high-end Dark Power Pro 10, are able to deliver the above mentioned low loads without problems. Even older models are mostly compatible with the fourth Core generation. In detail Dark Power Pro 10 (all models), Straight Power E9 (all models), Pure Power L8 (all models), System Power 7 (all models) and Pure Power L7 (630 W and 730 W) are fully Haswell compatible.