How Voltage rails work?

Ok - I'd like to upgrade my GPU and was considering:

EVGA GTX 560 Ti SC -- [Requires 500W, 12V, 30A PSU]

Now my 2-year old Antec EarthWatts 650W has three 12V rails, supplying 22A, 22A, and 25A. So obviously I'm out of luck, since I can't make the 30A requirement. (didn't realize 2 years ago that even mid-range cards would require such high currents)

Ok, so now I'm considering:

EVGA GTX 560 SC -- [Requires 450W, 12V, 24A PSU]

Now I'm in business, because I have one rail that supplies 25A. However, how do I know that the 25A rail is supplying the PCIe cable? It doesn't say anywhere on the cable which rail it connects to. Or are all rails connected to any cable through internal circuitry?

Any help would be very much appreciated.
3 answers Last reply
More about voltage rails work
  1. mrgrey said:
    Ok - I'd like to upgrade my GPU and was considering:

    EVGA GTX 560 Ti SC -- [Requires 500W, 12V, 30A PSU]

    Now my 2-year old Antec EarthWatts 650W has three 12V rails, supplying 22A, 22A, and 25A. So obviously I'm out of luck, since I can't make the 30A requirement. (didn't realize 2 years ago that even mid-range cards would require such high currents)

    Ok, so now I'm considering:

    EVGA GTX 560 SC -- [Requires 450W, 12V, 24A PSU]

    Now I'm in business, because I have one rail that supplies 25A. However, how do I know that the 25A rail is supplying the PCIe cable? It doesn't say anywhere on the cable which rail it connects to. Or are all rails connected to any cable through internal circuitry?

    Any help would be very much appreciated.

    The power reccomendation is for the entire system and refers to the combined 12v output , either card you mentioned would work fine, even if the rails were all 18a.
  2. A GTX 560 Ti would get power from the PCI-E x16 slot as well as two different PCI-E power connectors. These can all be different rails. Your PSU is fine for that card. Could possibly handle two in SLI.
  3. Ah, ok. I didn't realize you can add all rails to get total current. Thought they were separate, thanks very much to both of you. I'd select both as best answers, if that's possible.
Ask a new question

Read More

Graphics Cards Gtx EVGA Graphics