GTX 285 vs 2 X 4870 in crossfire

Discussion in 'Mac Pro' started by Abidubi, Aug 23, 2009.

  1. Abidubi macrumors 6502

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    #1
    Ok, I need some help getting some facts straight. I am considering upgrading from the 4870 to the 285. It's a fine idea except that the 285 is very expensive, but at least I could try and sell the 4870 and maybe get $300CAD for it. Then I thought, what about just getting a second 4870 and crossfiring them? I have read through a good 3 or 4 threads on these forums about powering the second card, flashing PC cards and working with crossfire... that was a freaking long 3 hours of reading non-stop.

    So I have these questions which I hope someone here can answer with reasonable certainty.

    1) When doing crossfire, do the cards have to be very similar for them to work? If 1 card is 512 and the other 1GB will there be any advantage over just getting a card with 512?

    2) If other cards of the same family work, would a crossfiring of the apple 4870 with a 4870X2 perform similar to 3 X 4870 in crossfire?

    3) Could someone explain the cables and/or hardware needed to power the second card from the second optical drive slot? I think the best way to go is 1 cable from each card to the regular spot and 1 cable from each card going to the same connector in the optical bay.

    4) Apparently 2 X apple 4870s don't work with crossfire. But does this apply to combining an apple 4870 with an unflashed PC 4870?

    5) I thought I read about some attempts to modify the ROM of the apple card to enable crossfire with some success. Is that true and if so where is this ROM and does it negatively impact the apple 4870 in OSX?

    6) If have read in the past (I think with the PC 3870s) that if you connect a second unflashed card to an apple card with the crossfire link that the card behaves in OSX (doesn't spin it's fans wildly). I don't need it to do anything in OSX except not blow up, I only care about it working in windows. I'd like to avoid flashing the PC card if I can.

    Thats about all I can think of for now. Thanks for the help.
     
  2. gzfelix macrumors member

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  3. Abidubi thread starter macrumors 6502

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    #3
    "I don't need it to do anything in OSX except not blow up, I only care about it working in windows. I'd like to avoid flashing the PC card if I can."


    Oh and I just had 2 jets (F-18 or something else, couldn't see them) do a full afterburner take-off over my house... love when those bastards do that, house rumbling and all.
     
  4. MattZani macrumors 68030

    MattZani

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    #4
    2 4870's will be alot more powerful than a 285.

    I Think if you have a Apple 4870 and a PC 4870, in OS X the PC wont do anything, and in Window, the Apple will work normally with the PC.
     
  5. Nugget macrumors 65816

    Nugget

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    #5
    With all the reported driver problems people seem to be having I'd suggest staying far away from the 285. For now, at least. The EVGA Forums are full of dissatisfied mac users. Kernel panics and flaky drivers that don't allow the card to work at full speed in OS X.
     
  6. Abidubi thread starter macrumors 6502

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  7. Tallest Skil macrumors P6

    Tallest Skil

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    #7
    CrossFire isn't possible in OS X. Period.

    CrossFire works with Apple cards in Windows, I believe.

    If you're using PC cards, don't screw with the ROM. Just install netkas' injector.
     
  8. MacVidCards Suspended

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    #8
    As Mathew Russo and I were discovering, the Crossfire support is TURNED OFF in Apple's ROM.

    There is NO WAY to use an APple 4870 in Crossfire without flashing it...once done it will be SECOND card in Crossfire, not first. (So, no good with 24" LED ACD)

    Read our efforts ...not sure where but you can find.

    The GTX285 issues are overblown, and bound to improve, as the 8800GT did with time.
     
  9. Abidubi thread starter macrumors 6502

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    #9
    I had been following your posts. I wasn't too sure whether you meant 2 apple 4870s didn't work or any combination involving an apple 4870.

    What do you mean once you flash the apple card it will work as the second card? Will it no longer work in OSX? Are you no longer able to run a display off of it?

    If it means I can't run a display off of it, can I connect the display to the PC card and it will still produce an image in OSX?
     
  10. Bubba Satori Suspended

    Bubba Satori

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    #10
    Stop it. Steve doesn't want you fiddling with video cards. :D
     
  11. Topper macrumors 65816

    Topper

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    #11
    Vocal minority. Some people like the GTX 285.
     
  12. Nugget macrumors 65816

    Nugget

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    #12
    Well if I had all those problems you can bet I'd be vocal too!
     
  13. Chad H macrumors 6502a

    Chad H

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    #13
    My MP is fixing to get an overhaul. I'm throwing my GTX285 back in with 2 corsair 64GB SSD's and they will be in RAID 0. I will have a 3rd corsair for Bootcamp gaming. Also installing 6GB of RAM. But, I will run complete benchmarks so you can look at the GTX285.
     
  14. brock2621 macrumors 6502a

    brock2621

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    #14
    The 4870's require TWO power connectors so there aren't 4 available in the stock mac pro's. You could run splitters but then you're over the limit for the power supply so you are going to need a drive bay power supply to run those things. Lastly, OSX doesn't support crossfire soooooooo.... not worth the extra investment basically.
     
  15. Cindori macrumors 68040

    Cindori

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  16. grue macrumors 65816

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    #16

    I'm not sure I entirely believe that the power supply can't handle it. I have the one of the most power hungry Mac Pro Apple has shipped (2007 8x3.0) with all the RAM slots full, 5 SATA HDDs (one of which is 10,000rpm), optical drive, GTX 285 and 8800GT installed, with no problems other than the creativity necessary to cleanly wire everything up in the first place.
     
  17. Cindori macrumors 68040

    Cindori

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    #17
    He is talking abot ports, not watt.

    Crossfire 4870 has already been done by users on this forum.
     
  18. grue macrumors 65816

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    #18
    He/she/it clearly states, and I quote:

     
  19. Abidubi thread starter macrumors 6502

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    #19
    Was that addressed to me? I already have the computer... since this one came out.

    And as to why I would buy a Mac if I intend to play some games on Windows despite the possibility for top of the line hardware and lower costs:

    A) I prefer OSX so so so much more than windows and use it exclusively for daily use. The OS is way better at multi tasking than windows is, which is a piece of crap from my experience.

    B) I already own software for OSX and don't want to buy it all again for windows.

    C) I would never touch a hackintosh, way too much trouble. Just flashing a graphics card is at the limit of what I want to do.

    D) I only have room for 1 computer so if I have to choose between windows or mac, mac wins hands down.

    E) I only use windows for a hand full of games that aren't available in OSX, totally not worth another computer to run that.

    F) I don't need the most powerful graphics card in OSX as the most demanding games never get ported to OSX with the exception of doom 3 and quake 4. The games that need crossfire, SLI or the latest and greatest tend to stay on windows.
     
  20. Abidubi thread starter macrumors 6502

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    #20
    As an update, unless the mac card can be flashed to work with crossfire I think I'll be buying 2 XFX 1GB 4870s and flashing 1 of them (unless I really need to flash both, only need 1 display in OSX).

    It's funny that the total cost in CAD including taxes and shipping is still about $50 cheaper than the apple 4870 before taxes.

    I need to figure out the cabling though. My plan is 1 apple funky connector from each card to the MB, then using 1 standard connector that comes with the card for each card. To connect them I would need to get a SATA to 2X molex, then get 2 molex y splitters I think. Would this work?

    [​IMG]
    Using 1 of these http://www.newegg.ca/Product/Product.aspx?Item=N82E16812226018

    [​IMG]
    Then using 2 of these to make a total of 4 female connectors http://www.newegg.ca/Product/Product.aspx?Item=N82E16812183147

    And then connecting 1 power cable from each card to it.
    http://www.newegg.ca/Product/ShowIm...deon HD 4870 HD-487A-ZHFC Video Card - Retail

    I can't tell due to the resolution of the picture, but are the card's connectors male or female molex? They need to be male with this setup.

    Also, how am I going to get the cables to the card? With the side cover on there is no room for wires.
     
  21. TheStrudel macrumors 65816

    TheStrudel

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    #21
    How are you wiring it, anyway? Using molex from ODD, or splitting the PCIe power junction? There's been much debate but no definitive answer as to which is safer.
     
  22. brock2621 macrumors 6502a

    brock2621

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    #22
    Mac Pro's specification are very clear and i quote, "300W combined maximum for all PCI Express slots".

    Whether or not they are fibbing... that's another issue...
     
  23. grue macrumors 65816

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    #23

    The top molex I leave unadulterated.

    Bottom molex is split into two molexes, one of which has a molex to SATA converter on it to power the HDD there, the other of which has a molex to PCIe converter on it. Then the cables all run through a small gap in the shelf and under the front fan.
     
  24. grue macrumors 65816

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    #24
    I believe that refers to the maximum supplied through the motherboard.

    FWIW, the specifications also say that you can only have 8GB of RAM in the quad core Nehalem, but we know that's not true as well :)
     
  25. brock2621 macrumors 6502a

    brock2621

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    #25
    LOL touche sir... ;)
     

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