What Power Supply Do You Need?

Seems today to be a popular question with your little dream build when your thought process finally gets to, "Oh Yeah, I also need a power supply?"

Today your P/S needs to be in the beginning planning stage not the end, in days of old it didn't matter, Watts was the thing, if you had a 350W P/S you were bad to the bone and had way more power than you needed.

Today performance video cards laugh at 350W P/Ss, so for you guys that suddenly need an answer to that burning question, "What P/S do I need for all this build I'm ordering?", maybe this post will help you.

For you to be on the safe side will require a little research on your own and video card wise what you put in that machine determines how much power is needed to run it.

Research your video cards requirements if the video card requires 20A 12v rail, get a power supply that will supply that power, if your video card requires 26A 12v rail, get a P/S that supplies what it needs.

You will then discover that the P/S that supplies the proper 12v rail amperage also covers the required wattage you need to power your system! Amazing!

You can find the recommended requirements listed either at the video card manufacturers website, or Newegg under Specifications, System Requirements, Newegg usually will list the exact requirements for the particular brand video card you're considering getting.

When it comes to an SLI or Crossfire setup your P/S choice is even more critical, and you need the power to push those cards and thats not the time to be scrimping with what you're hoping you can get by with.

When it comes to SLI or Crossfire I've learned the hard way that a Single 12v rail P/S design is the way to go, supplying enough amperage for both cards.

When the final choice is made of the P/S you're going to purchase take these things into consideration and be prepared to spend more on your P/S than the deal you were hoping to squeeze into the budget, and get yourself a P/S rated to handle what your system needs.

So later down the road when other systems are failing yours will be running just fine, and get yourself a P/S from a company that has been producing, and specializing in P/Ss all along, not a company jumping on the P/S bandwagon, that doesn't make the P/Ss themselves, and have direct control over quality control.

Take these things into consideration so you can make a decision that you won't regret later, that could in the end cost way more than you tried to save! Ryan
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  1. The following concerning Nvidia based Graphics cards is quoted from the Nvidia Forums, I can neither confirm or deny his statements so glean what you will from this information at your own expense.

    SmilesLikeJokerJun 29 2007, 09:35 AM
    As people purchase higher-end cards, it seems that most overlook the new power supply requirements. With that said, I thought I would make a quick reference post that lists the power requirement for G7 and G8 cards. Hope it helps someone

    There are two requirements that you need to check:
    Amps on the 12v rail(s)

    *Keep in mind these are the MINIMUM requirements. Power supplies run best best between around 70-85% of max load*

    Card--------------Amps 12v rail----Watts
    8800 Ultra 768MB---------34--------------500
    8800 GTX 786MB----------28--------------400
    8800 GTS 640MB----------26---------------400
    8800 GTS 320MB----------26---------------400
    8600 GTS 256MB----------22---------------400
    8600 GT 256MB------------22--------------350
    8500 GT 256MB------------18--------------300
    8400 GS 256MB
    8400 GS 128MB
    7950 GX2 1GB--------------27--------------450
    7950 GT 512MB-------------20--------------400
    7900 GTX 512MB-----------26--------------400
    7900 GT 512MB-------------20--------------350
    7900 GS 256MB-------------20--------------400
    7800 GTX 512MB------------26-------------400
    7800 GTX 256MB-----------26--------------400
    7800 GT 256MB-------------26--------------400
    7800 GS 256MB-------------18-------------350
    7600 GT 256MB-------------18-------------350
    7600 GT KO 256MB---------18--------------400
    7600 GS 256MB Passive---18-------------400
    7600 GS 512MB-------------18-------------350
    7300 GT 512MB-------------18--------------350
    7300 GT 256MB-------------18--------------350
    7300 GT 128MB-------------18--------------350
    7300 GS 256MB-------------18--------------250

    I know it's not an all exclusive list, but it lists the majority of the cards used today.

    Please keep in mind that this is the minimum for a single video card. These numbers do not take in consideration of the rest of your system. Also, overclocking your video card increases the power that is needed.

    I've already stated that power supply are most efficient around 70-85% load. Keep this in mind when looking at purchasing.

    Stick to purchasing ones that are made by companies that are known to produce quality power supplies. That $6.00 EBay special is that price for a reason. You get what you pay for.

    If you are planning to drop a few hundred dollars on a video card, make sure your power supply is up to the challenge. You just dropped a few hundred dollars on a video card. Don't cut yourself short on a power supply.

    Good Luck!

    Link to complete forum discussion
  2. I've gotta 8800 gts and I run a 300 watt power supply and it works great
  3. I had a 700 watt power supply running 2 7800GTX in SLI and after 1yr and 4mos it failed to supply the amperage the cards needed, so congratulations on your success, I sincerely hope it lasts for you.
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