Much has been made of the spectre of PSU incompatibility with the release of Haswell in June. The new spec defines two new low power states for a deep sleep mode defined as C6 and C7 which require a load on the 12V2 rail of just 0.05A, a change from 0.5A on Ivybridge. In many PSU's this could mean triggering under- or over-volt protection mechanisms, causing system instability. To address the lack of knowledge in this area Intel recently took the lid off this specific aspect of Haswell and the Z87 platform before the official launch date - a highly irregular move - and PSU manufacturers have been eager to catch up.

One such manufacturer is FSP, who have just announced their projected compatibility with Haswell looking at both this and the 18A on the 12V2 rail 'performance spec', and the news is promising. All recent PSU's, including the low power HEXA 400/500W lines should be capable of the latter specification, whilst the vast majority of the latest Aurum and Raider models should have no difficulty with C6/C7 states thanks to an early transition to Active-Clamp MIA IC Topology. Additionally Aurum PRO models are also compatible thanks to their LLC Full Bridge topology.

Users without a C6/C7 capable PSU need not worry too much. Motherboard manufacturers are expected to allow selective disabling of these states in UEFI; you won't get the full power saving benefits, but it should at least mean you won't suffer from an unstable system.

The following is a full list of FSP PSU compatiliby (revieced via Press Release)



Source: FSPLifestyle.com