1. Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

Rated PSU Amps and Wattage

Discussion in 'General Hardware' started by Relinquish, Apr 27, 2012.

  1. Relinquish New Member

    Joined:
    Jan 10, 2011
    Messages:
    126 (0.05/day)
    Thanks Received:
    15
    Hello,

    I was confused about something so I was wandering if anyone can help me out.

    Basically I have an OCZ 550W Fatal1ty PSu and whilst I don't have an issue with it, I was wandering something about the advertised amperage ratings. On the side of the PSU it says that there are 2 12V rails, each with a rating of 25 amps with a total advertised output of 450W (The other 100W is for the 5V and 3V rail).

    Is that not off?

    If I use the equation: power = voltage X current I get 12 volts X 25 amps = 300W per rail. So 600W for both rails no?

    I ask because Corsairs TX650 has 52 amps on a single 12V rail and is rated for 624W of output. Also I want to know what flexibility I have in terms of adding a decent graphics card (my one has been RMAd). I mean 150W is quite a big difference and will allow me a lot of breathing room. It may even be a misprint.
     
  2. Cotton_Cup

    Cotton_Cup

    Joined:
    Mar 19, 2012
    Messages:
    377 (0.20/day)
    Thanks Received:
    35
    Location:
    Rizal, Philippines
    550/12 = 45.8 so should be getting 45amps

    25amps each should not be that bad overall should be like 40amps or so in total if I'm right.

    imo if you can find one at a single 12 rail go for it. as single rails are more effective at least based to the peoples socks I've been smoking
     
  3. Naito

    Naito

    Joined:
    Oct 10, 2009
    Messages:
    725 (0.26/day)
    Thanks Received:
    369
    From what you're saying, your PSU can supply your system with 450w over two 25amp, 12v rails. The rails themselves can handle up to 25amps each, but using this formula, I = P÷V, we can determine your system can supply a total of ~37.5amps on its 12v system (overall, not per rail). When picking a PSU, amperes it can supply over the 12v subsystem, is arguably the most important thing to look for.

    It's often hard to find ampere recommendations of a GPU, but to give you an idea of my setup (look at my 'System Specs'); it'll pull a max of ~400w+ for the whole system under load (Prime95 CPU, MSI Kombustor Xtreme burn-in GPU). Using this information, I can determine my GTX 470 uses ~220 watt under load. Combined with a manufacturer rating of 42amps needed. I may not be able to use my system with your PSU, but a higher wattage PSU, yes.
     
  4. de.das.dude

    de.das.dude Pro Indian Modder

    Joined:
    Jun 13, 2010
    Messages:
    8,074 (3.18/day)
    Thanks Received:
    2,270
    Location:
    Pune
    both are 25A?

    there is a 90% chance that it isnt even a dual rail.

    also i suspect that the max output on either of the rails at a time is 25A.

    it says 450W so you have 37A on the 12V rail as a combined output.


    so if you deduct 150W from 450W for CPU and stuff, you can easily run a 250W graphics card.
    goto http://www.gpureview.com/show_cards.php/ to findout about graphics card power consumption. They have a really extensive database.
     
  5. Fourstaff

    Fourstaff Moderator Staff Member

    Joined:
    Nov 29, 2009
    Messages:
    9,348 (3.42/day)
    Thanks Received:
    2,098
    Location:
    Home
    You can probably draw 25A from either rail but not full 50A from both. At least that is my understanding.
     
  6. de.das.dude

    de.das.dude Pro Indian Modder

    Joined:
    Jun 13, 2010
    Messages:
    8,074 (3.18/day)
    Thanks Received:
    2,270
    Location:
    Pune
    yeah, like i said too.
     
  7. Cotton_Cup

    Cotton_Cup

    Joined:
    Mar 19, 2012
    Messages:
    377 (0.20/day)
    Thanks Received:
    35
    Location:
    Rizal, Philippines
    your better off with a single rail psu, less brain power needed ^_^ if you got the bread and can't decide go for 1500w psu at least that way you won't be thinking whether you lack power or so, since on computer, it's either you can afford it or not and if your willing to pay for it or not.
     

Currently Active Users Viewing This Thread: 1 (0 members and 1 guest)