GTX 285 + GeForce 8800 GT power supply?

Discussion in 'Mac Pro' started by madi81, Jan 7, 2011.

  1. madi81 macrumors newbie

    Jan 7, 2011

    I've now come across a well know problem - running two GPUs in an early 2008 Mac pro.

    Since the GTX is taking up both power supplies I don't know how to power my old GeForce 8800 GT. I've researched the net and there seem to be numerous ways to solve this problem - from a more powerful PSU to splitter cables etc. but since I'm not very techy and don't want to risk anything blowin up I wonder if the following easy solution is going to work:

    I want to get an external power supply like this one:

    instead of installing it inside the macpro I would just rest it on top of the tower and run an extension like this through the back to power the 8800 GT

    Is this going to work or are there any risks in doing so. What would happen if I forget to switch on the external power supply - would the card simply not work at all or perhaps only the fan wouldn't come on?

    As mentioned I'm not the most technical person if it comes to the interior of my MacPro but this seems to be the easiest and cheapest solution to make use of my old 8800GT as an additional card.
    Any other suggestions would be very welcome.


  2. Garen macrumors regular


    Apr 9, 2010
    Los Angeles Area
    If the 2nd card will not be used heavily you can put a Nvidia 120 or 7300, neither one requires power supply just what is supplied through PCI slots. The cards are cheap and you don't have to worry about PSU.

  3. madi81 thread starter macrumors newbie

    Jan 7, 2011
    elegant solution


    this would certainly be a very elegant and hassle free solution. I have thought of that myself in a way.

    Trouble is that really cheap second hand cards only sell in the US on ebay for example. With postage and import duty I would end up spending more than on the PSU to run my own card.

    If I find a cheap card that has no power cables in Europe I'll probably go for that solution. Besides this I can always sell my 8800.

    I am actually intending to only run a 21" Eizo to watch telly on the weaker card so performance is pretty irrelevant. My main 24" Quato screens are connected to the GTX 285 which works beautifully.

    thanks for the quick reply

  4. nanofrog macrumors G4

    May 6, 2008
    I'm not sure if you can find it in the UK, but there is a nice, inexpensive solution (ePOWER EP-450CD; $20USD here, but they don't ship to the UK). It stuffs in the empty optical bay out of sight.

    Maybe the Epower Where to Buy page will help (didn't recognize a seller that would ship to the UK). Pricing from a place that would may also make it too much of a pill to swallow (even before shipping and VAT).

    Otherwise, using a second card without the need for additional power cables would be the best alternative IMO as well (since your posts indicate that this is viable for your needs).
  5. madi81 thread starter macrumors newbie

    Jan 7, 2011
    future upgrades

    Thanks for all your helpful replies. Shame I can't hold of the ePOWER EP-450CD in Europe. It's so cheap and would have been a great solution.

    I'm still thinking my original plan from above wouldn't be that bad especially thinking of future upgrades. Perhaps I'll ad a second 285GTX at some point. I would need the extra power then anyway.

    Could anyone confirm that my plan from above with those products would work. I'm a bit confused about the voltage. Don't the cards draw 12V but the description of the extension cables says something about 6 volts. Are they too weak?


  6. nanofrog macrumors G4

    May 6, 2008
    I wasn't sure if it would be viable, either locating it in the UK/European market, or due to cost reasons if you had. Sorry it didn't work out. :(

    It won't be pretty to look at, but Yes, it will work so long as the PSU has the correct PSIG cables to do what you need (6 vs. 6+2 versions, depending on whatever card you choose requires). BTW, this implementation has been done before with an MP. :)

    As per turning the PSU on, you jump the green and black wires in the Main Board connector (won't work if you don't).

    The extension cable will work as well (6V is part of their part number, not 6 Volts). ;)

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