Sea Sonic Electronics and Corsair are gearing up for the next month's release of the Intel Haswell processors, and have starting to evaluate their power supply units (PSU) in order to see whether they can handle Haswell's extremely low power sleep states. Standard ATX power supplies that conform to the ATX 2.3 standard may not be capable of supporting Haswell's low power sleep states. When an Intel Core (i3, i5, i7) processor is idle, it goes into a sleep state that requires less power than when the CPU is active. Since the motherboard voltage regulation modules that provide power to the CPU gets their power from the power supply's +12V rail, these sleep states can dramatically reduce the load on the power supply's +12V rail. The Haswell chips will require 0.05A on the 12V rail as opposed to the ATX 2.3 minimum's 0.5A.

Even if the sleeping CPU is the only load on the +12V rail, most power supplies can handle a load this low. The potential problem comes up when there is still a substantial load on the power supply's non-primary rails (the +3.3V and +5V). If the load on these non-primary rails are above a certain threshold (which varies by PSU), the +12V can go out of spec (voltages greater than +12.6V). If the +12V is out of spec when the motherboard comes out of the sleep state, the PSU's protection may prevent the PSU from running and will cause the power supply to "latch off". This will require the user to cycle the power on their power supply using the power switch on the back of the unit.

Sea Sonic claims that its full lines of 80 PLUSR Platinum and Gold power supplies have been designed to be ready to meet Haswell's new technical requirements. The company's Platinum series and its X Series, which is now supported by the 80 PLUSRGold G series - are all Haswell ready. In addition, the Sea Somic 80 PLUSRBronze line up, consisting of the M12II-650, 750 & 850W models, is also compatible to be used with Intel's new Haswell Processors:

Sea Sonic PSU Series	Wattages
X Series	650, 750, 850, 1050, 1250
Platinum	660, 760, 860, 1000, 1200
Platinum Fanless	400, 460, 520
G Series	360, 450, 550, 650
M12 II Bronze EVO	750, 850

Corsair is still working with Intel on the details of the testing methodology they use to check PSUs for Haswell compatibility. However, it is already known that a power supply that uses DC to DC for the non-primary rails (the +3.3V and +5V) will not have an issue with the new low power sleep states. This is because a DC to DC buck converter is used to convert +12V to +3.3V and +5V. This means that no matter what load the CPU puts on the power supply, there will always be a load on the +12V because the +12V is required to provide power to +3.3V and +5V.

Corsair utilizes this DC to DC technology in most of their power supplies. Starting with the CX750 and CX750M and moving all of the way through the GS Series, TX and TX-M Series, the HX Series, both the AX Series Gold and AX Series Platinum, and the new AXi Series:

Corsair PSU Series	Model	Haswell Compatibility	Comment
AXi	AX1200i	Yes	100% Compatible with Haswell CPUs
	AX860i	Yes	100% Compatible with Haswell CPUs
	AX760i	Yes	100% Compatible with Haswell CPUs
AX (Gold and Platinum)	AX1200	Yes	100% Compatible with Haswell CPUs
	AX860	Yes	100% Compatible with Haswell CPUs
	AX850	Yes	100% Compatible with Haswell CPUs
	AX760	Yes	100% Compatible with Haswell CPUs
	AX750	Yes	100% Compatible with Haswell CPUs
	AX650	Yes	100% Compatible with Haswell CPUs
HX (Silver, Gold and HX1000)	HX1050	Yes	100% Compatible with Haswell CPUs
	HX1000	Yes	100% Compatible with Haswell CPUs
	HX850	Yes	100% Compatible with Haswell CPUs
	HX750	Yes	100% Compatible with Haswell CPUs
	HX650	Yes	100% Compatible with Haswell CPUs
HX (Legacy)	HX620	TBD	Likely compatible — currently validating
	HX520	TBD	Likely compatible — currently validating
TX-M (All Versions)	TX850M	Yes	100% Compatible with Haswell CPUs
	TX750M	Yes	100% Compatible with Haswell CPUs
	TX650M	Yes	100% Compatible with Haswell CPUs
TX (All Versions)	TX850	Yes	100% Compatible with Haswell CPUs
	TX750	Yes	100% Compatible with Haswell CPUs
	TX650	Yes	100% Compatible with Haswell CPUs
GS (V2)	GS800	Yes	100% Compatible with Haswell CPUs
	GS700	Yes	100% Compatible with Haswell CPUs
	GS600	Yes	100% Compatible with Haswell CPUs
GS (Legacy V1)	GS800	TBD	Likely compatible — currently validating
	GS700	TBD	Likely compatible — currently validating
	GS600	TBD	Likely compatible — currently validating
	GS500	TBD	Likely compatible — currently validating
CX-M	CX750M	Yes	100% Compatible with Haswell CPUs
	CX600M	TBD	Likely compatible — currently validating
	CX500M	TBD	Likely compatible — currently validating
	CX430M	TBD	Likely compatible — currently validating
CX	CX750	Yes	100% Compatible with Haswell CPUs
	CX600	TBD	Likely compatible — currently validating
	CX500	TBD	Likely compatible — currently validating
	CX430	TBD	Likely compatible — currently validating
VX (Legacy)	VX450	TBD	Likely compatible — currently validating
	VX550	TBD	Likely compatible — currently validating
VS	VS650	TBD	Likely compatible — currently validating
	VS550	TBD	Likely compatible — currently validating
	VS450	TBD	Likely compatible — currently validating
	VS350	TBD	Likely compatible — currently validating