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Opus with AMD's

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  • Opus with AMD's

    I am confused at how these AMD's are running off the opus. I looked up the specs on the AMD website ( here ) and it shows nominal voltage of 1.75V (example using xp 2k+) and a typical processor current of 35.7A. Using their calculation (found on page 5 here ) of Current (on 12V rail) = (1.25 x nominal voltage x processor current)/12. This equals 6.5A (example using amd athlon xp 2k+) on the 12V rail. Anyone have any ideas of how it is possible that the OPUS can supply the necessary power on the 12V rail when it max's out at 5A?

    Hopefully, someone has an idea so that I don't feel uneasy about buying the opus for my amd 1400 that wants to become a carputer. Thanks,


  • #2
    I don't think that the CPU (and motherboard in general) gets its power from the 12V line. I thought that the CPU is largely off the 3.3V line, though at 10 amps the Opus can't provide enough power on that line alone either. There's another 10 amps on the 5V line, so if it's some combination of the two, there's enough power there.

    I don't whether the Opus should be able to power an Athlon, but I can see how it could. Im sure other will debunk/second me here.


    • #3
      The AMD tech guide says that AMD processors use only the 12V rail.


      • #4
        Huh. Well then I agree with you, it shouldn't work. And even if it just barely did, you wouldn't be able to power drives.

        A thought: The Opus' may be capable of a fair bit above their rating. They could have a fairly wide manufacturing margin, or perhaps MTBF suffers. If that's the case, relying on it seems like asking for trouble.


        • #5
          Aren't these guys using the M version of the processor?


          • #6
            Strange! I was just reading this article ( and it says that the 2200+ I will be using requires only 1.65V. Maybe AMD's rating is 1.75V and these guys are saying it's stable down to 1.65V?

            I'll have to play with it a bit and see how low I can get the voltage to go. I was planning on running an Opus 150w PSU. Right now I have it running in my house off a 125W PSU out of a Shuttle case and it has worked fine so far.

            EDIT: I just read the PSU more carefully and it seems that it's actually rated at 220W. We'll see what I can get this CPU to do once I have an OS installed.
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            • #7
              From Anandtech article on the XP2000+

              The CPU itself still runs at a 1.750V core voltage and draws an average of close to 36 amps of current, dissipating 62.5 - 70W in heat.
              36 amps at 1.75 volts = 5.2A @ 12V (70W = 5.8A)

              However, that was almost the hottest CPU that AMD has made, and if you underclock it slightly (and it will still perform really well) then you can get the PEAK usage under 5A.

              However, this is all assuming that it will be running at full load all the time, which i seriously doubt it will! Put the multiplier at 10.0 or lower, and you'll still have good performance, and good power usage. Knock the voltage down (especially if you knock the speed down) and it will still be stable.

              The 2200+ is a Thoroughbred core (compared to the Palamino in the 2000+) and therefore uses a lot less power, so the default voltage is lower. I've ran a 1700+ Thoroughbred at 2200+ at 1.5V

              The Opus should be fine with it, as has been said, the Opus is quite conservative with it's power ratings (ie it can often do more than it says it can)

              Co-Developer of A.I.M.E.E