Haswell and PSU compatibility
We are all waiting for Haswell, Intel's latest CPU offering. One of its features is that it can go into very low power states, which is of more benefit to laptops than desktops, but does have implications for desktop PSUs. At the lowest power states, Haswell will only need 0.05A from the PSU, and not all PSUs can deliver such a small amount of power. For a more detailed look on this issue, read the relevant articles at Bit-tech, Tomshardware, or Xbitlabs.
What does that mean for you? You need to check whether your PSU can support Haswell's lowest power states. If your PSU does not, then you need to disable these states (rumours are that most mobo manufacturers will deliver their mobos with this feature disabled by default). The good news is that most high-end quality PSUs (and some mid-range PSUs) are already compatible with Haswell's low-power states. The bad news is that there is very little data available on this issue for the consumer to look up, so it is not easy to tell whether the PSU you have (or are intending to buy) will support Haswell's low-power states.
While information on ultra-low power from PSUs is scarce, PSU companies are trying to catch up. To its credit, Enermax quickly published a press release after this issue came to light, showing which of their PSUs are ready. Intel has a PSU selector, but the overwhelming majority of PSUs do not have the relevant info available (only a few Corsairs do). Corsair recently released a list of their Haswell-compatible PSUs. Silverstone also published a list for its PSUs. An Antec rep said that they are checking up on the issue, on the Jonnyguru forums.
PSUs on Logical Increments
Many of our recommended PSUs are fully compatible with Haswell, but some are not. We will continue to update this list as we hear from the manufacturers:
- Seasonic Platinum 1000: Meets spec. Source. Confirmed by Seasonic.
- Seasonic Platinum 860: Meets spec. Source. Confirmed by Seasonic.
- Corsair AX850: Meets spec. Source. Confirmed by Corsair.
- Seasonic X850: Meets spec. Confirmed by Seasonic.
- Seasonic X750: Meets spec. Source. Confirmed by Seasonic.
- Corsair HX750 (V2): Meets spec. Source. Confirmed by Corsair.
- Rosewill Capstone 750W: Probably meets spec. Source. (Rosewill customer service replied to us saying this PSU "should have no problem to work with Haswell and we are still in the process of releasing an official list")
- Seasonic M12II 750W: Meets spec. Confirmed by Seasonic.
- XFX Pro/Black/XXX 750W: Probably meets spec (Seasonic OEM). (Unconfirmed by XFX )
Outstanding - Superb tiers
- Seasonic M12II 620W: Does not meet spec. Source. Confirmed by Seasonic.
- Seasonic SS-650AM: Meets spec. Confirmed by Seasonic.
- Antec 620 HCG-M: Probably does not meet spec. Source. (Unconfirmed by Antec)
Great - Modest tiers
- Seasonic S12II 520W: Does not meet spec. Source. Confirmed by Seasonic.
Entry - Destitute tiers
- Seasonic S12II 430W: Does not meet spec. Confirmed by Seasonic.
- Corsair CX430 (V2): No data found yet. (Unconfirmed by Corsair)
- Antec Earthwatts EA-380D: No data found yet. (Unconfirmed by Antec )
- Seasonic SS300ET: Does not meet spec. Confirmed by Seasonic.
We want to thank Seasonic for responding to our inquiry with the exact relevant info, and we will update the list as soon as the relevant data becomes available from other companies.
All the PSUs listed above are quality units (for the price), so if your PSU is a quality unit, but does not meet Haswell specs, does that mean you need a new PSU to upgrade to Haswell? No, you do not. As mentioned earlier, you can disable the low-power states (or your mobo manufacturer will disable them by default), and you will be fine.
If you have any additional relevant info, please do not hesitate to contact us so we can update/correct the list. Thank you.