Cooler Master De-Mystifies Intel Haswell PSU Compatibility Issues

Our friends over at Cooler Master are helping us all out by ending the mystery around the new power state from Intel Haswell. I thank Cooler Master for stepping forward and clearing up a lot of misinformation that may be circulating about Intel Haswell and how power supplies will be affected.


The new power states C6/C7 allow a system to drop to 1W or less during idle mode instead of the 5W we use now. The issue is some older power supply units will shut off at such a low load especially for idle mode or sleep mode. This created a lot of confusion for customers planning to switch to Haswell on release, so lets clear all the confusion up right here and now with the most asked questions.

  1. Most power supplies don't support Haswell – False
  2. I need a Haswell certified power supply to build a Haswell system – False
  3. Haswell only works with DC-DC Power Supplies – False
  4. Haswell only works with 80+ Gold and better Power Supplies – False
  5. Haswell requires a second 12V rail and doesn't work with single rail Power Supplies – False
  6. On some older power supplies, Haswell consumes 5W more in idle mode - True

Cooler Master also states motherboard vendors will have the "advanced power saving" mode disabled by default so no one will have any issues. If you decide to enable the feature, most people will still have no issue. The hand-full of people who may experience the aforementioned power down can prevent this by connecting a single case fan directly to the PSU to increase the load.

I hope this information helps those looking to move to Intel Haswell in the near future. If you are still a little skeptical about if you are ready for Haswell or not, Cooler Master also provided a chart of all their units compatible with the new power states.

Cooler Master De-Mystifies Intel Haswell PSU Compatibility Issues

For more information on how Cooler Master is addressing Haswell compatibility, please check out the press release below.

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Cooler Master's PSU Haswell Ready

There has been a lot of talk about PSU compatibility for Intel's upcoming 4th Generation Core Processors (code named Haswell). We have observed a large amount of misinformation being spread. We would like to clarify the situation to calm and reassure our customers and partners that they will be able to upgrade safely. A full list of Cooler Master power supplies is listed here. Below are some quick facts that the public should be aware.

Most power supplies don’t support Haswell – False

I need a Haswell certified power supply to build a Haswell system – False

Haswell only works with DC-DC Power Supplies – False

Haswell only works with 80+ Gold and better Power Supplies – False

Haswell requires a second 12V rail and doesn't work with single rail Power Supplies – False

On some older power supplies, Haswell consumes 5W more in idle mode - True

Among other improvements of Intel's latest Core Processors, power consumption in idle mode has been greatly reduced from around 6W to less than 1W. This might cause some older power supplies to shut the system off when the CPU enters idle mode, or prevent the system from waking up out of sleep mode. To our knowledge all mainboard vendors will disable this advanced power saving mode by default, and no customer upgrading to Haswell should experience any issues whatsoever.

Should customers experience problems nevertheless, or would like to enable the advanced power saving mode on older power supplies that might not support it, there is a simple fix. Simply adding a single silent case fan to the system, connected to the power supply, should provide enough additional load to keep the system running in advanced power saving mode. The only disadvantage would be that power savings in idle mode on such a system would only surmount to around 2-3W instead of ~5W.


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