About my power supply

I have the Antec EarthWatts EA650 650W Continuous Power ATX12V Ver.2.2 / EPS12V version 2.91 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC "compatible with Core i7/Core i5" Power Supply

Alright, this power supply has 3 12V rails, one with 22A another with 22A and the last with 25A.

What does this mean? To put it simply.
I've seen most with just one rail, rating of 40A or something of the sort. Does that mean my PSU only can provide a maximum of 25A, or do they combine in values? And what would be the benifit of having 3 12V rails, with ratings as so
5 answers Last reply Best Answer
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  1. Best answer
    The second line of text below the picture tells you the wattage available on the 12 volt rail, divide wattage by voltage to get amperage, 540/12=45A. Because the various loads are spread out among the rails, fairly evenly, your PSU can provide up to 45 amps of power on the 12V rail, however, if you use a bunch of molex to PCI-E adapters and try to use it to run a GTX280 or a similarly power hungry card, then the current rating for each rail applies, if you try to draw more than 22A from either of the first two rails, or more than 25A from the third rail, or more than 45A of power from any combination of the 3 rails, the PSU will shut off. Having multiple rails doesnt provide any advantages or disadvantages, and in fact most of the time they are a single rail anyway so it doesnt really matter.
  2. Thanks for your reply, you gave me a very nice answer and explained it well. I'm still learning about power supplies. Can you explain more throughly what the 12V rail is? The information would be really nice to know.
    Out of all the connectors of a power supply, which is the 12V rail?
    1 x Main connector (20+4Pin)
    1 x 4 Pin ATX 12V
    1 x 8 Pin EPS 12V
    6 x Peripheral
    6 x SATA
    1 x Floppy
    2 x PCI-E

    Is it the main connector? Cause i'm pretty sure my 4 pin ATX connects to my CPU, SATA's to my harddrive and DVD drive, Main connector to my motherboard.
    If my Graphics card doesn't connect directly to my PSU, how does my PSU apply propper amperage to it?
  3. Any yellow wire you see is +12V, the blacks are all ground. The Peripheral connectors provide both 5V and 12V power, SATAs provide 12V, 5V, and 3.3V depending on what the device needs. The PCI-E connectors supply all of their power from the 12 volt rail, and the majority of the power that the motherboard draws is from the 12 volt rail. About 80% of the power in a modern system comes from the 12V rail which is why the majority of the wattage that your PSU can provide comes from the 12V rail.

    Some of the pins on the PCI-E slot of your motherboard are they to provide power to the card in the slot. The slot is capable of providing up to 75 watts of power. Something important to realize however is that your PSU does not apply amperage, it has the ability to provide the current if the item tries to draw the power, the PSU does not force the current into the item.

    If you want to learn more about PSUs i suggest you read through this PSU FAQ by jonnyguru. Jonnyguru specializes in power supply reviews, its a very informative FAQ and will probably teach you more than you need to know, but more isnt bad.
  4. Thank you, i will look into it.
    Since the slot can only provide 75 Watts of power to the power supply if it needs it which is very nice to know, then i guess that how my graphics card gets its other power is from wire that it connects 2 on the motherboard. It's a very small wire, 2 pins, a little south east from the PCI-E slot.

    This is the graphics card i have, it says it needs 26A variable to work properly in your system, and its installed in my system so i know its recieving the ampage somehow.
    Since the slot does not apply amperage, thats the only conclusion i have come to so far.
    I will read into it, or maybe you can answer this for me
  5. No. the little 2 wire connection is for audio.

    The 6 pin connectors plug into the back of the video cards.

    BTW, the 6 pin connectors are not interchangeable with the 4 and 8 pin connectors.

    The 26 amp requirement is an estimate of the power needs of the complete system.
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