'The Deal' On Mac Pro Video Card Compatibility

Discussion in 'Mac Pro' started by slughead, Sep 6, 2006.

  1. slughead macrumors 68040


    Apr 28, 2004
    [REPOST FROM AI--post your thoughts/corrections please]

    I've decided to start a new thread because some exciting stuff is going on (some fresh news in here for people who don't know, read on!):

    EFI, Apple firmware, and ROMs.. how does it all fit together?

    From what I've found out, most modern video cards are EFI as well as BIOS compatible. (1)

    'PC' video card ROMs are only 64K, whereas 'Mac' cards are 128k. The reason for this is so that Apple can have full-color and full-resolution boot sequences and boot menu (what you see when you hold down option).

    Therefore, whatever ends up happening, all PC video cards on a mac (if they run at all) will have a black screen until the OS loads the driver. This hand-off between the video card's ROM driver and the OS driver occurs just before the login screen. (2)

    Whenever you hear about people soldering in new ROM chips to a PC video card to make them work with a Mac, this is why.

    YOUR MAC WILL NOT BOOT without a Mac Video card in the slot AND a monitor connected to it (4)

    Why PC Video Cards don't work (or do they?)

    Actually, PC video cards work FINE in a Mac Pro (2), it's OS X that doesn't work.

    OS X needs a driver to run these cards, which demonstrated by the fact that at least two PC 7800 GTs have been reported to work out of box. (2)

    Before you ask, they were PNY and eVGA brands (2) (The eVGA Part No was 256-P2-N515-AX) (4).

    In both cases, the stock 7300 (Mac w/128k ROM) was left in slot 4 and a monitor plugged into that card.

    How could this happen, you wonder, if the only OS X driver for the 7800 is for PPC and not x86? Simple: the G70 chipset used by the 7800 GT is also present on the ... you guessed it, QUADRO! (cue the oooooohhh's).

    But the PC x1900's don't work with mac, and they have a driver!

    Well, perhaps they do. There has been 1 report of an x1900 XTX [sic.] working out of the box in a mac pro, but that was unsubstantiated and the poster has since disappeared from existence. (3) Apparently, the card was detected as an XT, not an XTX.

    It would not suprise me if at least one manufacturer had some sort of weird chipset which other people who've tried x1900's did not have, and that chipset may work with the Mac Pro.

    It could also be that some people who have tried the x1900 did not wait to see if the 'black screen' would go away. Again, the temporary 'black screen' is normal, so we know that even a card that WORKS would have this issue.

    Finally, people need to leave an Apple card plugged in and a monitor connected to it or their machine will not boot!(4)

    Fun Facts

    - The Mac Pro has a 1KW PSU.
    From barefeats:
    -Can you use Windows PC PCIe graphics cards in a Mac Pro? No. The Mac Pro requires special firmware.
    -Can you use G5 PCIe graphics cards in a Mac Pro? No. They have different firmware.
    -Can you take a Mac Pro PCIe graphics card and run it in a Windows PC? YES! You may say, "Why would you want to?" But this points to the fact that a company like XFX or ATI could, if they want to, release a "PC and Mac Pro" version of their graphics cards.

    -SLI DOES WORK in the Mac Pro, though it should be noted that there can only be ONE 16x slot, so there may be no point. Here are the possible PCIe configurations (configurable by software):
    . .  .  .  .  .  . Slot 1 .  .  . Slot 2 .  .  Slot 3 .  .  Slot 4
    Option 1 .  .  8-lanes .  .  8-lanes .  . 1-lane .  .  8-lanes
    Option 2 .  .  8-lanes .  .  8-lanes .  . 4-lanes .  . 4-lanes
    Option 3 .  .  16-lanes .  . 1-lane .  .  1-lane .  .  8-lanes

    So that's the news as I see it, here are the sources:

    1: http://strangedogs.proboards40.com/index.cgi?board=experiments
    2: http://forums.macrumors.com/showthread.php?t=230505
    3: http://discussions.apple.com/message.jspa?messageID=2916283#2916283
    4: http://forums.macnn.com/65/power-mac-and-mac-pro/308387/pc-pcie-video-card-working/

    Clips from source 2:

    REPORT 1:

    REPORT 2:

  2. Fedge macrumors regular


    Aug 9, 2006
    This is an excellent summary. Thank your so much for rounding this all up for us. Hopefully we can update this thread as new details become available.
  3. aiongiant macrumors 6502a

    Aug 8, 2006
    sweet summary
    hopefully we can all get this working on the Mac Pro! :D
  4. superorc macrumors newbie

    Sep 4, 2006
    Actually, on my 7800GT I can get the bootup menu to work and it shows the grey screen, but if I left the 7800GT plugged in OS X crashed.
    Also, when I do the switch, it takes about a good 7-8 secs for my display to come up after switching the cable, probaly because OS X is detecting the display.

    EDIT: Looks like someone else even found out before me but no one noticed it. So that's 3 so far. http://forums.macrumors.com/showpost.php?p=2753628&postcount=124
  5. slughead thread starter macrumors 68040


    Apr 28, 2004

    Well that's confusing as hell. I'll update this in a few minutes. I based a lot of this on your experience as reported here and on macnn :)

    Edit: I wonder if that guy with the 4 LCDs has this prolem
  6. Ebonweaver macrumors newbie

    Jun 26, 2007
    Small but important error

    While it's true the system will not boot without a video card being recognized, it will absolutely boot with no monitor connected. We run a lot of headless systems here without problem.
  7. ndriver182 macrumors 6502a

    Jun 26, 2007
    Is the x1900xt the only higher-end card really available for the MP these days or are there any other options? If the x1900xt really is the only one to be looking at, can it be from any company besides directly from ATI?
  8. azkgtr macrumors newbie

    Nov 12, 2007
    mac pro video cards

    Hey guys,

    I was recently able to get mac pro to boto natively without boot camp into windows XP and so with this i purchased the proper apple 6pin power conenctors for the 8800 series video cards, the same cable for the appel ATI X1900XT.

    The cards scored very well in 3DMark06 11.2k i believe with 1GB of ram and a 500GB samsung HDD. Here is my question

    IF i boot camp the APPLE so i have the original 7300GT plugged in at the bottom port and have the 8800GTS640MB running at the top PCIE slot will this work? and how will windows which Video card to use for 3D rendering

    any ideas?
  9. fredr500 macrumors regular

    Apr 12, 2007
    Still confused

    OK, I'm still confused. I have the stock Geforce in my mac pro, and want to add a 3rd monitor. Do I have to use an Apple card, or can I use any PC Geforce 7300? Or can I use something else? I'm not worried about gaming performance, I just want to run Fusion full screen on 1, OS X with Photoshop or FCS on the other 2.

  10. Macinposh macrumors 6502a

    Jun 7, 2006


    What if you have a 30" on the 7300GT (mac original) and a 22" in the 8800GTS(aftermarket), what would show up in OS X? A blank 22"?
    What in windows? A full 22" and a black 30"?
    Or a exteded desktop?

    Or has anyone managed to get the 7300 series (upper slot x4) and 8800 series (main slot x16)to work together?
    Like,you could run the os x normally,even if you would have the nonworking 8800 pluged in the pci16 port?
  11. Eidorian macrumors Penryn


    Mar 23, 2005
    If you want to use the cards in OS X you're going to need to either get an Apple card or a PC video card flashed to be a Mac one.
  12. rhildinger macrumors member

    Oct 11, 2006
    I was never able to get my Mac Pro to boot at all whenever I had an Apple 7300GT and a PC 8800GTS installed at the same time, no matter what slot configuration I used, and I tried several.

    The Apple X1900XT, however, does not seem to have this problem. I have had this card installed at the same time as a PC 8800GTS and the Mac Pro would boot into OS X just fine. It just wouldn't recognize the PC video card. I also tried the same thing with a PC 8800GT and that also worked.

  13. cuestakid macrumors 68000

    Jun 14, 2006
    San Fran
    after reading this and several other forums I have a couple questions which is likley a dumb one but would still like to know.

    I understand that the Mac Pro won't boot with the pc graphics card inside-but what happens if I simply move the monitor connection? If there is no signal to the pc card wouldn't it simply use the mac card? Also, how would I power the card? Do I need a special connector from apple?

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