Early-2009 Mac Pro - The GPU Dilema

Discussion in 'Mac Pro' started by GeneralAntilles, Sep 13, 2009.

  1. GeneralAntilles macrumors member

    Jan 5, 2002
    Thanks to a leaky G5 I've netted myself a new dual-2.26GHz Mac Pro. I went ahead and ordered a Radeon HD 4870 from Apple, but I need another graphics card to go with it. It looks like I have a number of options:

    1. Second Radeon HD 4870 - This is an appealing option because it offers a lot of performance, but it's also prohibitively expensive and eats up two PCI slots between the heatsink and the power supply.
    2. GT 120 - The only supported option, but the Mini DisplayPort on the GT 120 and its anemic performance make it less than desirable, but it is single-slot.
    3. Radeon HD 3870 - Seemingly a nice compromise between options 1 and 2, but it would require figuring out a workable power arrangement (4-pin Molex to 6-pin PCIe adaptor off the 2nd optical bay?) and the reports of excessive fan noise are off-putting. It's priced similarly to the GT 120, however (when you add in the Mini DisplayPort adaptor) and actually provides two dual-link DVI ports while still maintaining the single-slot form factor.

    I went ahead and ordered a GT 120 since I suspect I can make use of a 3rd graphics card anyway, but am still wondering whether the 3870 would make a more desirable secondary card.
  2. Dr.Pants macrumors 65816


    Jan 8, 2009
    Running more than two displays? Just curious.

    1. Its a trap!* The second 4870 will require another PSU, methinks that was the general consensus here. You can fit one in the second optical bay that is made for that form factor.

    2. Be careful if you plan to run Windows Vista native - it doesn't like the mix-and-match of ATI and nVidia GPUs (wheras 7 and Xp do like both, IIRC)

    3. Maybe the second PSU again? I am not sure how people have fitted this in their MacPro.

    Not sure - I can remember reading around here that the 3870 was not OpenCL capable, something to keep in mind. J the Ninja posted this.

    Have you considered flashing any of the above cards? Also, what uses will your computer be put towards?

    *I understand that Antilles and Ackbar are two different characters, but I couldn't help it :eek:
  3. GeneralAntilles thread starter macrumors member

    Jan 5, 2002
    Probably 4 or 5 depending. Two Samsung 2343bwxs, a Samung 206bw, a Samsung SyncMaster 941bw and a 20" 1st-generation aluminum Apple Studio Display.

    It obsoletes Exposé. ;)

    Yes, I'm aware of the power requirements, thus the issue of it absorbing all of the additional PCI slots. It's out thanks to the cost and double-wide heatsink anyway.

    Yeah, I could care less about Windows, but thanks for the heads up. ;)

    That might be an issue, although it only requires one additional 6-pin PCIe connection (versus the 4870's 2), so it seems like powering it off the optical bay should be feasible.

    A notch against the 3870, then.

    I have, but so far my impression has been that the flashed cards are only capable of outputting video on a single DVI connection which makes them mostly unusable for my purposes. However if this is not the case, then I'd love to be able to save the money.

    Everything from text editing to 3D rendering and gaming. I have no issue maxing pretty much any hardware I can get my hands on. ;)
  4. Dr.Pants macrumors 65816


    Jan 8, 2009
    For certain!:eek: I can't think of SPACE for those displays on my desk without ergonomics.

    Nope, just one. Take a look. The GT120 at the bottom is in the first slot, and there is space for a double-wide card. :)

    Certainly, but I don't know the requirements of the 3870 off the top of me head, but certainly do-able.

    A very unfortunate one, IMHO :(

    I was under the impression that the flashed 4870s could use dual-DVI but lose the ability to output VGA.

    Heh. Awesome. Might consider a processor upgrade ;) People do it (as well I next year). However, the dual-core system looks trikier to upgrade then the quad....
  5. GeneralAntilles thread starter macrumors member

    Jan 5, 2002
    One monitor arm, a speaker, some monitor stacking and a little bit of desk modding. ;)

    Sadly, yep. The Two Radeons occupy slot 1 and 2, the heatsink on the second covers slot 3 and the power cable for the optical-bay PSU covers 4. See here and here.

    Ah, maybe it is that. Dunno, but it'd be nice to have an authoritative answer.

    Considering it when the 5500-series prices come down next year. Although the potential for failure scares me a bit on the dual-CPU machines.
  6. J the Ninja macrumors 68000

    Jul 14, 2008
    Keep in mind, I'm just an armchair poster on this sort of thing. I don't know how to code OpenCL.. I'd like to learn, but I have no idea how hard it would be. (Good God, I really don't know Python. Or CSS for that matter). I don't claim that thread to be 100% correct. How I became the some sort of OpenCL expert for this fora is a bit of a mystery to me. As a note, I've read some other statements (that I really didn't understand) which said the HD 3000 series isn't OpenCL capable. Although it does have programmable shaders, it's lacking some other features that are pretty much essential. Supposedly these aren't totally implemented on the HD 4000 series either, and this is responsible for their abysmal OpenCL performance.
  7. Dr.Pants macrumors 65816


    Jan 8, 2009
    If you need the PCIe x4 lane on top, couldn't one route power through the front of the bay? I know, tacky, but hey, if it works.... :)
  8. JesterJJZ macrumors 68020


    Jul 21, 2004
    Just get a second Mac Pro and sit it next to the one you got. :D
  9. GeneralAntilles thread starter macrumors member

    Jan 5, 2002
    Yeah, or I bet I could probably dremel the heat exhausts on one of the 4870's to slip the cable through there, too. Either way, not enough money.

    Yeah, but a second Mac Pro wouldn't be coming on-the-house from Apple. ;)
  10. matthewtoney macrumors regular


    Aug 17, 2009
    Charlotte, NC
    Since you are apparently running the same config as myself (single 4870 combined with a GT120) care to comment on *any* games you have tried or possible usage of VMware Fusion? I'm trying to confirm what seems likely as a conflict with these two cards combined.
  11. GeneralAntilles thread starter macrumors member

    Jan 5, 2002
    Still waiting on my Mac Pro to ship from Apple. They quoted me another 7-10 days. :\
  12. GeneralAntilles thread starter macrumors member

    Jan 5, 2002
    Just to update, I ordered the GT 120 and have an in on a cheap 3870, so I'll run some tests and see what's what once everything gets here.
  13. TheStrudel macrumors 65816


    Jan 5, 2008
    I would point out that a Radeon 2600 will work just fine with the 4870. And plenty of people have successfully flashed 4870s that work with two displays, and a lot of the people who only had them working with one DVI port found that problem magically fixed by Snow Leopard.

    Also, people have run two 4870s with no additional PSU - just by using a Y-splitter on the PCIe power traces from the logic board, no molex connectors involved. There was a whole thread on this.
  14. Justinf79 macrumors 6502


    May 28, 2009
    I noticed in the pic that the two cards are hooked up in crossfire. Does OS X support crossfire, or is that just for windows? :D
  15. Whiteyez macrumors regular

    Mar 17, 2009
    OS X does not support crossfire or sli, only windows. :(

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