What´s up with the Watts?

Is there a way to calculate which type of PSU you´re going to need for a specific system? I´ve heard that new generations of video-cards requires a quality PSU of atleast 350-400W. I´m running my system on a 230W PSU and I´ve never had any problems. I´ve run Prime95, Sandra Burn-in-test and played Battlefield 1942 for hours on the Net without any problems at all. I´ve even overclocked my system, and lowered my memory timings quite a bit, and it´s still perfectly stable. I know it may be because I´m only using one harddrive and one CD-drive, I´m just wondering if you can precisely calculate what type you´re going to need for your system.


<A HREF="http://forumz.tomshardware.com/modules.php?name=Forums&file=profile&mode=viewprofile&internal=1&username=Sir_Lovesalot" target="_new"> My system </A> :cool:
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  1. No, not really. Even if you could accurately predict what your components are drawing for wattage (I imagine a 15,000 rpm drive would take a lot more than say a laptop ~4000 rpm. Also, a Pentium chip will draw would draw a little more power than a celeron chip. A 9500Pro is going to take more power than a 9600Pro). If you could accurately predict the wattage, than you have the problem of power supplies. For example, a 350watt good name brand power supply, such as enermax, may be equivalent to 450 generic no-name power supply. Then again, there have been instances where the opposite is true.
    If you're looking for a power supply to power your rig with the latest and greatest in it, I would say go with 400/450 name brand power supply. Antec, enermax, vantec, are good starts, and i'm sure forum members could recommend some others
  2. heya Sir_Lovesalot;

    There are generic charts for calculating an approximate total wattage usage value, unfortunately i dont know where one is off the top of my head to link you to it.

    I can tell you that from what i've seen only the latest graphics cards have a PSU wattage recommendation, these include R9800 Pro, Geforce FX 5800 - 5900, to name a few. So if you dont have one of these beasts your probably ok.

    One piece of advice for you.

    You will notice if you pay attention that alot of PSU manufactures list the Max and Continuous wattage output.
    Continuous is important because it lets you know how much wattage you will have at 100 percent duty cycle.
    For instance if your PSU is rated at 500 Watts max and 300 Watts Continuous, then it will do 300 watts for 100 percent duty cycle and 500 watts maximum output at a lesser percentage duty cycle.

    So pay attention and buy a TRUE POWER - PSU.

    Im no expert on Power supplies, so i only think this information is correct, if its not im sure someone will chime in and correct me hehe

  3. hmm i not quite sure about that duty cycle thing xeen. But one great argument to get a huge power supply ( i got a 530w enermax one) is the greater effiency. You'll create less heat and the fan will spin slower. As a suggestion its ideal to run your power supply to 70-75% of its max rating.
  4. heya jurians;

    Ive got a 550 watt Max PSU.
    The continuous Wattage is 290 watts.

    With this configuration the PSU outputs 290 watts at 100% duty cycle, however beyond its rated continuous wattage output the percent of the sustained duty cycle decreases as it aproaches max rated wattage, so as the wattage output increases the percentage of the duty cycle decreases untill you are at 100% max wattage and 1% duty cycle.

    This is how i interpreted the explaination by Crashman, however i could have misinterpreted the explaination.

  5. hmmm that acutally sounds right.. i havent made a power supply or a generator for a while. I'll think about it when im at work.
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