Intel Core i “Haswell” Microprocessors May Require New Power Supply Units for PCs

Intel Core i “Haswell” Chips May Be Incompatible with Existing Power Supply Units

by Anton Shilov
04/30/2013 | 11:03 PM

Intel Corp.’s Haswell microprocessors due in early June are expected to bring a number of innovations designed to improve performance and cut power consumption, however, in many cases not all users will be able to enjoy all of them. As it appears, end-users will either have disable low-power states of Haswell or get a new power-supply units compatible with the new Intel chip.


As it appears, Haswell's C6/C7 states require a minimum load of 0.05A on the 12V2 rail, and many desktop power supply units (PSUs) just cannot provide that low current, reports The Tech Report web-site. Numerous older PSUs, which comply with ATX12V v2.3 design guidelines that only called for a minimum load of 0.5A on the CPU power rail, can be equipped with a less sophisticated internal feedback loop/protection, reports VR-Zone web-site. As a result, unless C6/C7 power states are disabled in the BIOS, PCs with older/cheap PSUs may become unstable when processors enter these states.

To make the matters worse, many power supply units do not report minimum currents supported by 12V2 rail. As a result, it is now hard for system makers and end-users to determine whether their PSUs are Intel Core i-series “Haswell” compatible.

LGA1150 socket for Intel Core i-series 4000-family "Haswell" microprocessors. Image by web-site.

"I fully expect the [motherboard] companies to disable C6/C7 in the BIOS (though consumers could enable it if they chose to) as there are simply too many PSU's in the market space which might not work correctly. Corsair is working to ensure that all of its power supplies support the C6/C7 states. We believe they already do but are checking,” said Robert Pearce, validation program manager at Corsair Memory.

Intel did not comment on the news-story.