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Haswell Could Have Compatibility Problems With Older PSUs

By - Source: VR-Zone | B 37 comments

Older or cheaper power supplies might have compatibility with the upcoming Haswell CPUs because they are too efficient.

Yesterday, we gave you a full roundup of all the rumors that we have reported regarding Intel's desktop lineup of Haswell CPUs. In the meantime, yet another rumor has surfaced. According to VR-Zone, a number of power supplies will actually not be able to support the Haswell CPUs, not because they cannot deliver enough power, they cannot deliver a low enough level of power.

While the Ivy Bridge CPUs had a minimum power consumption of 0.5 A in a C6 or C7 state, the next generation of processors would require only as little as 0.05 A, a 10x reduction. The problem is that a number of older or lower-quality power supplies are unable to deliver such low loads at stable voltages, meaning that the system could crash due to unstable voltages when in C6 or C7 state.

Fortunately, there is a solution. Users with problems could simply go into the motherboards' BIOS interface and disable the C6 and C7 power states. However, this would lead to higher power consumption. Fortunately though, most modern power supplies shouldn't have issues with the low power draw. A number of manufacturers are already advertising power supplies that have perfectly stable voltages even down to 0 W, among which is Enermax.

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  • 38 Hide
    ccovemaker , April 30, 2013 3:00 PM
    Stable voltage at 0 watts....ummm interesting science.
  • 26 Hide
    webbwbb , April 30, 2013 2:11 PM
    Good. This will hopefully get people to throw their fire hazards (that is how I officially refer to cheap power supplies when talking to customers).
  • 23 Hide
    pbrigido , April 30, 2013 2:41 PM
    In other news: If you are building a new system with a Haswell CPU, use a new power supply.
Other Comments
  • 26 Hide
    webbwbb , April 30, 2013 2:11 PM
    Good. This will hopefully get people to throw their fire hazards (that is how I officially refer to cheap power supplies when talking to customers).
  • 23 Hide
    pbrigido , April 30, 2013 2:41 PM
    In other news: If you are building a new system with a Haswell CPU, use a new power supply.
  • 38 Hide
    ccovemaker , April 30, 2013 3:00 PM
    Stable voltage at 0 watts....ummm interesting science.
  • -4 Hide
    Rune Olsen , April 30, 2013 3:26 PM
    W00t, something is terribly wrong here with my single post
  • 1 Hide
    maui67 , April 30, 2013 3:33 PM
    It will be interesting to see how off-the-shelf manufacturers handle this, especially in inexpensive machines. They will need to start putting quality PSUs even in the low-end machines. I am sure the big boys like Dell and HP will be fine, but what about E-Machines and the such?
  • 5 Hide
    halcyon , April 30, 2013 3:49 PM
    Quote:
    It will be interesting to see how off-the-shelf manufacturers handle this, especially in inexpensive machines. They will need to start putting quality PSUs even in the low-end machines. I am sure the big boys like Dell and HP will be fine, but what about E-Machines and the such?


    PSU oems will just start making cheap units that support the new CPUs. There will be enough demand to justify it.
  • 0 Hide
    Memnarchon , April 30, 2013 3:50 PM
    "However, this would lead to higher power consumption."
    The question is how much?
  • 1 Hide
    vmem , April 30, 2013 4:02 PM
    LOL, in comes CUSTOM WATER COOLING. throw in a pump, and one or a few high powered GPUs, and you have a "high enough" powerdraw at idle :p . of course, all those people should not be running crappy GPUs
  • 4 Hide
    InvalidError , April 30, 2013 4:17 PM
    Most cheap PSUs already have internal loads (resistors) to guarantee the minimum load they need to remain reasonably stable.
    Where Haswell may be more of a challenge to cheap PSUs is response time to large load swings when the CPU keeps bouncing between C7 and full-power: too little feedback bandwidth means the voltage rails will sag when the CPU wakes up which may trip under-voltage lock-outs or surge when the CPU goes to sleep and trip over-voltage lock-outs. Depending on how fast Haswell can switch from full-power to sleep, the PSU's feedback delay could potentially encounter situations where the CPU is already going back to sleep while the PSU is still ramping up from the previous wake-up or vice-versa.
  • 0 Hide
    milktea , April 30, 2013 4:25 PM
    Quote:
    Stable voltage at 0 watts....ummm interesting science.

    Why so interesting? 0W means 0A at whatever voltages. It's like removing the Processor from the socket and measure the voltage being delivered at the socket pins.
  • 4 Hide
    InvalidError , April 30, 2013 4:26 PM
    Quote:
    Stable voltage at 0 watts....ummm interesting science.

    Nothing special/interesting about it: a Lithium battery delivers ~3.6V/cell open-circuit voltage, a fresh alkaline battery delivers ~1.65V/cell, a lead-acid cell delivers ~2.35V, etc. Mains voltage is 115-120V regardless of whether or not you have anything other than your multimeter plugged in. Your PSU's 12V rails are expected to hold 12V regardless of whether or not you have anything plugged in, same for 3.3V and 5V outputs.

    Voltages can exist without a load. Voltages and electrical fields are everywhere; even in the vacuum of space.

    Electrical current (measured in Amperes) on the other hand does require some form of conductor and load to exist.
  • 1 Hide
    gsxrme , April 30, 2013 4:39 PM
    Don't purchase cheap PSUs? and their's some real POS power supplies out there too
  • 1 Hide
    punahou1 , April 30, 2013 4:50 PM
    Maybe Niels could be a bit more specific in regard to the exact difference between an "old PSU" and a "modern PSU"...
  • 0 Hide
    Pinhedd , April 30, 2013 5:33 PM
    Cheap power supplies are the bane of my existence
  • -1 Hide
    amoralman , April 30, 2013 5:44 PM
    I hope they don't come up with the "Your mouse sensor system is obsolete when using Haswell CPUs. We recommend you upgrade your mouse to an approved model to fully experience what Intel has to offer"... :( 
  • 2 Hide
    math1337 , April 30, 2013 5:47 PM
    If your PSU fails at zero load, you're doint it wrong. Every decent power supply should be able to pass the zero load test, where it operates with the pins shorted to turn it on, and nothing plugged in as load.
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