Power Thinking.

Discussion in 'Mac Pro' started by Tesselator, Apr 22, 2013.

  1. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #1
    OK, I'm not Einstein so obviously this is me trying to think of a solution to some power requirements. Specifically the power requirements of a dual 6-pin GFX card as placed inside the MacPro1,1 - which to my knowledge only supplies one 6-pin socket.

    Some facts (please correct if mistaken):
    • Each 16x wired (not configured) PCIe slot has 3" wide traces running through the Main Board at 80ohms capable of supplying 75W each. ("Wired" refers to a full length 16x sized connector whether or not it can or is actually "configured" to operate using 16 lanes. I only briefed the PCISIG specs so I may have misunderstood - it could also be independent 75W traces for every other slot and not each slot.)

    • The 6-pin MB socket is similar and also capable of supplying 75W. It should not be over taxed and asked to supply up to 150W by using a simple splitter - If this is done then when the card actually draws that much instability and system crashes will likely occur. In some rare cases of prolonged use at those levels it could also potentially damage the main-board.

    • The SATA II power connecters are rated at either 10W or 20W (I forget) each and they also should not be asked to supply more - for the same reasons.

    • The MacPro1,1 PSU is more than capable itself of supplying power to 6 HDDs, two x5365 processors, the NB, eight 4GB DIMMs, ODD, the MB, Fans, and a 250W GFX Card - with just a little room to spare.

    • The GTX 570 for example is a 220W card. During peak usage in (name of intense game here) the PSU would be at about 85% or 90% of it's max rating - which shouldn't harm it if the fans ramp up to proper speeds.

    • With the ODD stuffed full of drives there is no place in the MP1,1 case large enough to place an additional PSU unless it's one of those long-thin looking shuttle types and even then the only place for it would be shelved just above the GFX card covering up slots 3 and 4.

    Here-in lay the dilemma; with all of those things connected there is no place to actually draw the power from. No connection (or even pair of connections) rated at the 75W needed for the second 6-pin connector. Except of course the three remaining PCIe 16x (wired) card edge sockets - (Which I believe have traces rated for 75W each if indeed Apple (Actually Intel designed the MB so... Intel) adhered to the standards set forth by the PCISIG (see assumed fact at top of list).

    What are some possible solutions?

    I have thought of:
    • Highjacking (piggy-backing, splicing, whatever) some 12V rails directly from the PSU.
    • Running the secondary PSU externally (yuck!).
    • Syphoning power from the empty PCIe edge connector sockets (not sure exactly what this would entail).

    The third option C, sounds the most interesting to me - personally. I looked around for a manufactured product but couldn't find anything. The closest thing I could find was "EVGA Power Boost" (P/N: 100-MB-PB01-BR) but if I'm not mistaken that's actually the opposite of what I'm looking for. It feeds 12V molex power (10 or 20W - I forget) into the adjacent PCIe slot (I think).

    What say you all? Options? Solutions, Products? Opinions? Whatcha got?
     
  2. GraniteTheWolf macrumors 6502

    Joined:
    Mar 31, 2013
    Location:
    Wisconsin
    #2
    I have a 1,1 and my GTX 570 works perfectly inside of it. Also yes my 1,1 has 2 6 pin leads on the logic board to power up my video card:
    [​IMG]

    Nothing special done required to make it work.
     
  3. Tesselator thread starter macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #3
    Wait, what? The MP1,1 has two 6-pin connectors on board?

    Seriously? I only noticed one last I was in there. Where's the second one?
     
  4. bax2003 macrumors 6502a

    bax2003

    Joined:
    Dec 25, 2011
    Location:
    Belgrade, Serbia
    #4
    Here it is :)

    [​IMG]
     
  5. Tesselator thread starter macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #5
    Right next to the one I just accessed last month? OK, its official, I'm a moron. :) Or as Roseanne Rosanna Danna would say... N-e-v-e-r-m-i-n-d :p
     
  6. TheEasterBunny, Apr 23, 2013
    Last edited: Apr 23, 2013

    TheEasterBunny macrumors 6502

    Joined:
    Jan 22, 2013
    Location:
    Delaware
    #6
    Fan shroud, and poor lighting?
    We all need an excuse, here is yours;)

    Maybe it's time for "The Mac Pro Borg addition" all add-ons on the outside, with cool wires and those pleated hoses and lights all flashing!
     

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  7. Tesselator thread starter macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #7
    Hehehe... It's missing a pair of boomed shock-mounted Heil PR-40's and a Meizler Collection Red.
     
  8. Shrink macrumors G3

    Shrink

    Joined:
    Feb 26, 2011
    Location:
    New England, USA
    #8
    That was Emily Litella....not Roeseanne Rosanna Danna!!

    Please, this is a technical thread, precise accuracy is everything!!:eek:

    ;)
     

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