Corsair outlines Haswell PSU compatibility

Written by Antony Leather

May 10, 2013 // 12:53 a.m.

Tags: #corsair #corsair-outlines-haswell-psu-compatibility #haswell #haswell-c-state #haswell-psu-problem

Corsair has outlined compatibility between its PSUs and Intel’s forthcoming Haswell CPUs. It's statement follows recent concerns over new sleep states introduced with its new CPUs. We recently reported that Haswell’s new sleep states, C6 and C7, can potentially drop the power consumption to just a tenth of that of Ivy Bridge CPUs.

This is great news for laptop battery life, and we’re certainly not against better power efficiency in PCs either. However, this low voltage could be a problem for current PSUs; at the very least there may be issues coming out of sleep, with Corsair stating that some PSUs - not just its own, use technology that could require a complete reboot, while other reports we’ve seen go as far as saying memory content corruption could also arise.

Thankfully, the vast majority of its current range appear to be future-proof, although as Corsair might be hinting at in its statement, the issue begs the question about whether Intel's R&D department was unaware of the issue or just keeping quiet, with responses from PSU manufacturers so far rather knee-jerk affairs. Referring to Intel's presentation at IDF, Corsair’s statement reads as follows:

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.

While we are still working with Intel on the details of the testing methodology they use to check PSUs for Haswell compatibility, 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 is 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. So whatever your budget, if you choose Intel's new Haswell processor and wish to utilize the new, low power C7 sleep state, Corsair has a power supply for you.


You can see the full statement as well as a complete list of Corsair’s Haswell-compatible PSUs and those it's currently checking here. Are you concerned about your PSU being compatible with Haswell's new sleep states? Let us know in the forum.

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