Geforce 8800 gt wont run two 30 monitors

I have two 30" monitors: one is Apple Cinema Display and another is 3007 WFP Dell.
My 8800 GT for Mac refuses to run them together.
Apple display works fine but Dell blacks out. Leaving a Dell alone I get perfect 2560 x 1900 resolution!

My 8-core Mac pro has also a stock card Radeon HD 2600.It works exactly the same way as 8800 gt. No dual monitor capacity with either card?
Help! I can't believe it.
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  1. Why not try them in a proper computer?
  2. What proper computer? Don't understand your question.
    Both cards are Apple product, only one of monitors isn't. What can be possibly wrong with me using dual display with Mac Pro and a GeForce 8800 GT specifically designed for that purpose?
  3. Ones an Nvidia product and the other is an ATi product and have (can) you try them in a machine that is not an Apple?
  4. I don't have a different machine and I doubt that a card, specifically designed for the Mac can be run on a PC.
    I repeat: I tried two monitors with the ATI card - Dell blacks out.
    I got a GeForce 8800 GT, installed it into a second slot - the same story. Dell alone works fine with either card. As a part of a dual display - blacks out.
    I wonder if Dell is only partially compatible with Mac. I used this Dell for a year on a PC before switching to Mac Pro completely.

    I'd like to see if anyone too, used dual display with one non-Apple unit.
  5. So are you running both the 2600 and 8800 at the same time? What if you run one monitor on each display, or did you already try thing.. Your wording gets a little confusing.

    What happens if you have JUST the 8800 installed and put both displays on that, what happens? Does the 2600 have dual outputs? what happens if you try both on that card without the 8800 installed?

    Another though, are both the DVI cables you are using Dual Link DVi cables?
  6. Both cards installed. At this moment, ATI card sits idle, a 8800 GT is connected with dual DVI cables. I tried every combination of connecting two monitors .
    Dell works at a maximum resolution with either card - alone, - fine.
    As a part of dual display with 30" Apple - blacks out.
    ATI card is the original for this Mac. I tried it first, as it has two dual-link DVIs - no luck. An 8800 GT too, has two dual-link DVIs - and can't run dual monitor. Only one at a time - either card.
  7. I am not familar with Macs, but I know in windows you have to go into Display Settings and enable the 2nd display, otherwise it would be blank.

    Another though is, and I can't say this for SURE, but it is possible that the cards have a max combined resolution of 2560x1600. Dual 1920x1200 would work, but not 2560x1600. What if yo use the resolution lower and then try it? Just a thought.
  8. Both cards should be capable of driving dual 2560x1600. As Jay said though, in Windows at least, one of the two would be black when you first plugged it in. To get the dual monitors setup properly, you would need to go into display properties and enable and configure the second display.

    I'm not at all familiar with OSX, but my guess for a good place to look would be the same place you would change resolution and monitor settings. See if there's a way to enable dual monitors in that area.
  9. viza said:
    I don't have a different machine and I doubt that a card, specifically designed for the Mac can be run on a PC.

    Well since Mac's actually use commodity hardware now both cards will work with any OS (hence the reason boot camp works....).

    As everyone has already said you need to go configure the display to be activated, if you have done this already then you have a problem otherwise it is just misconfiguration. If you do have an issue following the directions linked to (first search result on the search linked, also linked directly) then please re-post at that point.

    Google is your friend int his respect:
  10. Thank you for your input, gentlemen.
    You're all right.
    I am not novice to setting up hardware and I swear, it's all set properly. I'm afraid, all those claims about graphics cards running dual 30" monitors are simple overstatement.
    Or, at least, that dual display should have two similar panels.
    I'm looking for advice of someone who had similar with mine, problem.
    There aren't many 30" models on the market and I'm sure several people have multiple displays of different makers.
    I cannot be alone with this problem.
  11. I'm about to buy/try the 8800 GT on my 2006/07 Mac Pro 1,1 .. which now has stock 7300 GT card running two Apple Cinemas – a 30 plus a 21. So I'm not in your exact same situation.. but close. Hoping to run same 2 monitors off the new 8800 (really 9800) and get a performance bump. My dumb question (since haven't yet received my new board) is can't you run one 30 off one card, one off other? or will I find there's not enough slot horsepower for that setup... ? sorry in advance .. this post not very helpful for your specific question.
  12. I got a E2008 Mac Pro, with Nvidia's 8800 GT. I run two screens, one 21 inch NEC crt, the other one is 24 inch flat Dell. The only issue was Dell putting my Mac to sleep it could not wake from....more like coma than sleep. Problem was refresh rate. Fixed that and never had any issues since.
    And than yesterday my GT8800 pretty much died. My computer boots fine 'cuz i can hear it working, but my screens freeze on gray apple logo, there are weird random group of pixels on it, image of the turning gear echos somewhere on top of screen, than I get thick blue horizontal stripes on top of that gray screen, than turns all blue, and than my monitors display some patterns and colors I wont even try to begin to describe. Any one had this Mac-ical show happen to em?
  13. I don't think he can try the 8800GT or 2600 on a PC, the Mac editions have custom firmware & drivers.
  14. viza said:

    My 8-core Mac pro has also a stock card Radeon HD 2600

    8 Cores? Huh?
  15. Mac pros are dual socket.
  16. Yes, I have a Mac Pro with two Quad Xeons.
    Tried use of one monitor per card, no luck - Dell blacks out. Getting rid of it. Not fully compatible with Macs in such a configuration, I think.
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