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Thread: Need help choosing a new PSU

  1. #1

    Default Need help choosing a new PSU

    3 online calculators gave me 3 different values; 430W, 538W, and 850W. So my question is, what is closest to the truth? My full build can be found here: http://pcpartpicker.com/b/DXmG3C
    I'm looking for a modular PSU with a red LED fan in it to go with my build, so if anyone can give me any suggestions, it would be deeply appreciated. Kind of liking the look of the OCZ Fatal1ty PSUs, but not sure what size would be best. Or, if they don't have one close to the size I should use, what my next choice should be.

    Or, should I just crack my current one open and try replacing the fan in it? Doesn't look too hard, and I can use the same fan as the others in my case so it all matches.

    And if this is in the wrong forum, please forgive me. Still feeling my way around tis site lol.

  2. #2
    Why must hard drives fail together? TheMainMan's Avatar
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    Default Re: Need help choosing a new PSU

    What's the issue with your current PSU?

    While I've used a ton of the OCZ ModXstream PSUs in the past, I'm not sure I would go with an OCZ again due to the financial issues they've had. I know Toshiba bought the SSD division but I'm not sure what happened to the PSU division. If you try to check out the OCZ site for PSUs, there are a lot of broken links leading me to believe that support might be an issue.

    When picking a PSU you want to try to get as close to the average Watts your computer uses, while still maintaining some headroom for upgrades or expansion. Most online calculators vary in what they think is an acceptable margin and that is part of why you could have some very different suggestions. Bigger is not always better as power supplies are more efficient under higher load levels than near idle, which means that you're wasting power as heat if you're PSU is too big.

    For the parts you listed the only real concern I see is the number of amps the pair of 9800 GTs draw. From what I could find about them, you're looking at around 40-45A on your 12V line if they are running full out. Online PSU calculators vary depending on the database they use for wattage values and how specific you can get in terms of parts you account for. PCPartPicker estimates you only need 304W with that config and they are pretty good at having most values in their database.

    Long story short, if you run your graphics cards hard with games or 3D applications I would suggest something 80+ Gold or higher in the 500 - 650W range. Personal preference for me is Corsair PSUs, in your case probably an HX650.
    TheMainMan

  3. #3

    Default Re: Need help choosing a new PSU

    Thanks for the help There's nothing wrong with my current PSU, at least not in terms of functionality. It has a blue LED fan in it that clashes with my black/red theme. I am debating on either changing out the fan, or just getting a new PSU all together. I figured if I get a new one I should do it right. I also plan on mounting the PSU upside down in my case and cutting a hole on the top for the fan so the air flow is independent and to add to the external look of the case.

  4. #4
    Why must hard drives fail together? TheMainMan's Avatar
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    Default Re: Need help choosing a new PSU

    Ahhh, okay. If you decide to change the fan, a word of caution: try to leave the PSU unplugged for a couple of days or be very, very careful not to touch the large capacitors! I speak from experience that being shocked while working on a PSU is a very scary experience. Some PSU fans will have a standard connector and some are soldered directly to the board which makes swapping them a pain. You should be able to tell safely just by taking the cover off, just remember to respect the fact that you are dealing with the most dangerous part of your computer.

    Good luck!
    TheMainMan

  5. #5
    Anodized. Again. Konrad's Avatar
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    Default Re: Need help choosing a new PSU

    An important question which cannot be answered by the data on your build specs:

    How much do you wanna spend?

    Buying an "oversized" 850W or higher PSU now not only gives you some confidence after seeing the high-end online calculation - it also provides a scalability buffer for when you decide to upgrade your system in the future. You can avoid paying more a few years down the road if you already have a good enough PSU to deliver oomph on a new pair of crazy graphic cards. Or when you want to add a few more Terabytes of storage. Or when you want to plug 50 USB devices online. Or whatever.

    Buying a "barely sufficient" PSU now means that you don't have a lot of headspace on your system. You may need to endure sacrificing the possibility of overclock-level performance. You may even sacrifice base-level performance if various system components throttle down when other system components need to hog the power load. You can plan on adding the cost of a new PSU on top of any other upgrades you obtain.

    An over-rated PSU will not consume more power than a proper-rated PSU if no devices are actually consuming the power. That is, if your system pulls 600W then your electrical bill will cost 600W regardless of how uber your (at least 600W) PSU might be. (Well, this is a little bit exaggerated. Uber-rated PSUs are designed to perform best at uber-rated loads, there's always some engineering/efficiency tradeoffs in play. But the reality is that the "extra" power draw under non-optimal loading is basically a trivial consideration.)

    Higher-rated (and, alas, higher-cost) PSUs are generally more robust and invariably have better-rated components. If nothing else, a heavy-duty PSU will derate less under thermal stress, so it can run hotter longer before failure (but more likely, it will not run as hot while delivering "light" loads).

    I'm of the opinion that a fair rule of thumb is PSU cost should be roughly 15-20% of total system cost (unless, at the extreme-end, costs skyrocket and options are limited). Methinks that instead of spending more than this on a bigger and badder PSU, better bang for the buck can be achieved by purchasing a UPS or similar device.

    And hey, you can always keep your favourite monster PSU for years and years, it can probably outlast several motherboard swaps and major system rebuilds, in chassis after chassis. Worth buying quality, not worth buying cheap.
    My mind says Technic, but my body says Duplo.

  6. #6

    Default Re: Need help choosing a new PSU

    I found many videos and guide on choosing a new PSU on web. One of the best is mention below.
    http://www.pcworld.com/article/20254...er-supply.html

  7. #7
    Fresh Paint
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    Default Need help choosing a new PSU

    Thanks for the help. Ive actually decided on the Canon t2i since i want the HD video capture also. I just have to figure out what lens is right.

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