How much wattage do I need?

Hello,

I am planning on building my first computer. Could somebody please give me an estimate on how much wattage I would need in my PSU for the following build?

CPU: i5-2500K
CPU Cooler: Noctua NH-D14
Motherboard: ASUS P8Z68-V LE
GPU: ASUS Radeon HD 6850
Memory: Corsair Vengeance 8GB (2x4GB) DDR3 1600 Low Profile
Optical: LITEON Blu Ray Drive
HDD: Western Digital 3TB 6Gb/s IntelliPower
SSD: OCZ Revo Drive 3 120GB

A little extra wattage would be helpful for extra fans on the case.
12 answers Last reply
More about wattage need
  1. For a system using a single Radeon HD 6850 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 26 Amps or greater and have at least one 6-pin PCI Express supplementary power connector.

    Total Power Supply Wattage is NOT a crucial factor in power supply selection! Total Amperage Available on the +12V Rail(s) is the most important.
  2. Quote:
    Total Power Supply Wattage is NOT a crucial factor in power supply selection! Total Amperage Available on the +12V Rail(s) is the most important.


    I have not heard anything about this. Could you possibly elaborate more on it or direct me to a source where i can learn more about it? Thank you.
  3. AndrewK1 said:
    Quote:
    Total Power Supply Wattage is NOT a crucial factor in power supply selection! Total Amperage Available on the +12V Rail(s) is the most important.


    I have not heard anything about this. Could you possibly elaborate more on it or direct me to a source where i can learn more about it? Thank you.

    The two devices that consume the majority of the power, within the computer, are the CPU and the GPU(s). Both of these devices obtain all of their power from the +12 Volt rail(s). If this critical rail is unable to supply enough power to both of these components the system is not going to run properly.

    The motherboard's chipset, hard disk drive(s) motor, optical disk drive's motor, CPU cooling fan(s), case cooling fans, PCIe expansion cards also draw their power from the +12V rail(s).

    You can buy a 500 Watt PSU that has a combined +12 Volt continuous current rating of 23 Amps and it won't properly power a system running with a single Radeon HD 6850.

    You can also buy a 400 Watt PSU that has a combined +12 Volt continuous current rating of 30 Amps and it will properly power a system running with a single Radeon HD 6850.

    The PSU's total wattage is only used as a guideline, not the determining factor.
  4. So would the following PSU work the system posted above?

    http://www.newegg.com/Product/Product.aspx?Item=N82E16817139012
  5. AndrewK1 said:
    So would the following PSU work the system posted above?

    http://www.newegg.com/Product/Product.aspx?Item=N82E16817139012


    "Single +12V rail design providing up to 52A"

    Yes, that is a very good psu.
  6. Yes, easily.

    That power supply actually has enough headroom to allow you to Crossfire HD6850's without issue later on if you wanted. (if you have the proper motherboard)
  7. AndrewK1 said:
    So would the following PSU work the system posted above?

    http://www.newegg.com/Product/Product.aspx?Item=N82E16817139012

    The Corsair Professional Series HX650 (CMPSU-650HX), with its maximum +12 Volt continuous current rating of 52 Amps and with its four (6+2)-pin PCI Express supplementary power connectors, is way more than sufficient.
  8. So that would work with an upgrade in a year or two? Good to know. Thank you all!
  9. AndrewK1 said:
    So that would work with an upgrade in a year or two? Good to know. Thank you all!

    It will depend on what you are upgrading to.
  10. probably something like radeon hd 7970 but i will upgrade my whole system and just keep the case and PSU probably
  11. AndrewK1 said:
    probably something like radeon hd 7970 but i will upgrade my whole system and just keep the case and PSU probably

    For a system using a single Radeon HD 7970 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 36 Amps or greater and have at least one 6-pin and one 8-pin PCI Express supplementary power connectors.

    It'll work.
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