ATI 4870 + ATI 3870 in 2008 Mac Pro - my potential solution

Discussion in 'Mac Pro' started by KevinPlusPlus, Mar 14, 2009.

  1. KevinPlusPlus macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #1
    I couldn't find any references to anyone doing this yet and wanted to ask if I'm missing anything.

    I have a 2008 mac pro and 3-monitor setup. I originally started with 2 x ATI 2600's, but have since replaced one of them with a 3870. So, my current setup is 1 x 3870 and 1 x 2600. This setup has worked fine.

    Now that the 4870 is available, I'm looking to upgrade. I'd like to use 1 x 4870 and 1 x 3870. Obviously the 4870 would be the primary card and the one that bears the brunt of the GPU load, but I'd prefer the 3870 as the secondary card to the 2600 because the 3870 gives smoother performance with Quicktime in full screen for high-quality H.264 and also manages Spaces / Expose more fluidly, among other things. Plus, seems like a waste not to use it. :)

    The problem is the power - 3 PCI Express auxiliary power connections are required to run both cards. But I think I have a way to solve this. I can install a 4-pin molex splitter in the optical bay, and then use the included 4-pin molex to PCI Express power connection included with the 3870 along with a PCI Express power extension to feed power to the 3870, and then give the 4870 both of the motherboard power connectors.

    According to my research, I don't see much potential here for a power draw problem. The 3870 would be basically 2D only, and the max draw according to the table I found for 2D was somewhere in the 40 watt range, well within what the PCI Express slot itself will provide. Even in the freak condition that more power is required, the max draw was still under 100 watts, putting the draw on the auxiliary at 25 watts, which is comparable to one optical drive burning a DVD. Since it's highly unlikely that BOTH optical drives would be burning DVDs at the same time as maxing the video card out, I can't see how this could cause any stress on the power supply in terms of the power reserved for the optical bay (now split to the 3870) and the regular PCI Express power draw for both cards. Even if the power load was split between the bus and the auxiliary, that's still less than 50 watts on each, and theoretically the optical bay power can provide 50+ watts if it's within spec to burn 2 DVDs at once.

    But... am I missing anything? Or, has anyone else tried this? Thanks in advance!
     
  2. Wormy23 macrumors member

    Joined:
    Jul 1, 2008
    #2
    I think this looks like a valid configuration. The MP power supply should be able to handle it.

    One thing you might want to think about is that you mentioned you have a 3 monitor setup. Since the 4870 is the more powerful card, you probably want 2 displays on that one. It only has 1 DVI connector and the other is a mini DisplayPort so you may want to get on of those adapters from Apple to run it there.

    If you don't mind running 2 displays off the 3870, then you should already be set.
     
  3. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #3
    Thanks for the reply! I'm glad you think that this looks OK. Actually, since I posted, I found some more power consumption charts and it looks like for idle and 2D, the 2600 and 3870 are about the same, and only differ (and by pretty big amount) in 3D. Since it'll be the secondary card, it really shouldn't be any different from a power point of view than the 2600, or at least not by much.

    I actually did throw a mini displayport to DVI adapter in my order with the card, and of course it will be here weeks ahead of the card itself. :( Hopefully the 5-7 weeks is a conservative estimate and we see them sooner. At least we know they actually exist, unlike the 8800 in the last generation that delayed the CTO Mac Pros too.
     
  4. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #4
    It works!

    I can report that I have successfully installed the 4-pin molex splitter in the optical bay and run the extension down to the 3870. The computer is working fine and I didn't get the error when I booted about the power connector, so it seems that the power is actually reaching the card. And no, I haven't tried burning DVDs in both drives and running 3D to the max to see if anything explodes. :p

    I did need to use an extension beyond the splitter and the molex->PCI Express connector. I got a 12 inch PCI Expression extension although that really is too long, 6 inches would be plenty. Basically, the splitter + included cable reach to about where the ports are on the motherboard.

    So, now both of my motherboard connections are available for when the 4870 finally arrives. But first, I think we'll need to see 10.5.7. :cool:
     
  5. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #5

    i was thinking of the same set up (eventually). The 3870 + 4870 on a 3x display setup. I thought the MP 2008 could handle both cards without extra power?
     
  6. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #6
    The 3870 does not require the extra power, but rather strongly suggests it and you will be warned when you boot OS X if it's not connected. If you never used the 3870 for 3D you could probably get away with not connecting it.

    The 4870 requires 2 power connectors and I have no idea what would happen if you didn't connect them - anything from the computer not turning on to crashes to a meltdown on your motherboard. I'm not sure anyone really wants to find out. ;)
     
  7. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #7
    i currently just have the stock 2600XT card in my MP. I have a 3870 arriving in the next 3 days. I thought I could just slot it into the 2nd PCI Express 2.0 slot and be done with it. Are you saying its "recommended" to hook up an extra power cable to give it extra power in case it needs it?

    Then in a month or two, I might order the 4870. The 2600 will probably be taken out and gather dust. So I'll have a 3870 + 4870 card setup. so in total are you saying I need THREE extra power connectors?!? :eek:
     
  8. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #8
    Yes, the 3870 recommends use of the auxiliary PCI Express power. It comes with the necessary cable.

    The 4870 requires 2 auxiliary PCI Express power connections. And therein lies the trouble; the Mac Pro has only 2. So, to use a 3870 + 4870, you need to get a 3rd PCI Express power connection. I chose to get mine as described above by splitting the molex power cables in the optical bay.
     
  9. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #9
    could I bother you to take some photos of how/where the cable is connected to?
    Also with your 2600 + 3870 combo, does it matter which slot you have the 3870 in? 1st or 2nd, or doesnt matter. Btw is your 3870 fan noisy?

    Where did you get the cables/splitters from? can you post pics of your connections please :D
     
  10. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #10
    It's not very easy to photograph inside my Mac Pro due to where I have it. Where the cable connects on the motherboard and to the card will be obvious once you get the card, and it comes with instructions. So, this shouldn't cause you any stress.

    Which slot you have the cards in (slot 1 vs. 2) doesn't matter in 2008 or 2009 Pro.

    My 3870 fan sounded like a vacuum cleaner so I replaced it with the Accelero S1 Rev 2, which has no fan and is silent. You can find several threads on this cooler here on these forums.

    The molex to PCI Express cable comes with the card. The extension cable I got from Newegg; do a search there on CB-6M-6F .

    Hope that helps.
     
  11. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #11
    ok no worries :) i wouuldnt want to move my MP if its difficult to access

    Re the Accelero S1 Rev 2 cooler, doesnt that stick up quite a bit? I've read the 4870 is noisy too -- what then, dont think you can put coolers on both and still insert them into the PCI 2.0 slots
     
  12. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #12
    The Accelero cooler makes the 3870 a 2-slot card. So you can have the 4870 in slot 1 (which is double-wide), the 3870 in slot 2 (blocking slot 3 with the cooler), and still have another card in slot 4. I have an eSata card in my slot 4.

    I have not heard the 4870 in person but most folks seems to say it is reasonably quiet at idle.
     
  13. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #13
    thanks for the clarification.

    it seems like a lottery, some people say that their 3870 is silent other say it sounds like a hair-dryer to a hovercraft. just doesnt make sense. i've also read someone saying if you get a blue card its npisy, if its a red card its ok, or the reverse. what colour is your card and when did you get it?
     
  14. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #14
    The official Mac + PC edition cards are all blue as far as I know, and yes, there seem to be more hair dryer versions out there than ones that have a properly working fan. I got mine about a month ago, and even RMAed the first one but the second was no different. The aftermarket cooler almost seem to be a given unless you want to try card after card after card until you get a good one.
     
  15. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #15
    i think there was a typo. did you get yours about a MONTH ago?
     
  16. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #16
    Yes, sorry, that's what I meant. I corrected my post.
     
  17. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #17
    yipes, i ordered mine last week, and its enroute. that means ATI hasn't fixed the fan issue :eek: wtf. with enuff people RMA'ing their 3870's you'd think they'd have fixed 'em :confused::rolleyes:
     
  18. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #18
    I'll be curious to hear if you were a lucky one. Did you order from macsales.com or ATI, or elsewhere? Mine were from macsales.com.
     
  19. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #19
    from MacSales :eek::eek: EEEK! and its being 'processed' in customs. omg, i think i sprouted a white hair in the last 10 seconds to your last post
     
  20. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #20
    I don't think it really matters where you get them from. Macsales probably has some the highest turnover in inventory and since the card has been out since last summer, I think they just have some sort of design flaw.
     
  21. MacVidCards Suspended

    Joined:
    Nov 17, 2008
    Location:
    Hollywood, CA
    #21
    I always find it odd that Apple chose the single slot 3870. If you look carefully, it only uses a 2 wire fan. As far as I know, it is either impossible or difficult to control fan speeds with just 2 wires.

    The "Silver Arrow" OEM model (I believe) and the red Dual-slot PC and flashed versions use a 4 wire fan. And as the fan is MUCH larger, it can turn at a reduced speed to move the same quantity of air. So, an inferior fan on an inferior interface for speed control.....again I ask, WHY DID APPLE SETTLE FOR THE CHEAP 3870?

    The 4870 uses a proper dual-slot fan with 4 wres for proper speed control. It is nearly inaudible at idle.
     
  22. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #22
    DHL just dropped it off. Should I take it to the local church to get it blessed first before I install the card?
     
  23. mbimac macrumors member

    Joined:
    Apr 1, 2009
    Location:
    vancouver
    #23

    Hey which version do you use? PC or Mac , I am using the same as yours'
    I am also interested in upgrading to HD4870 thanks
     
  24. KevinPlusPlus thread starter macrumors member

    Joined:
    Sep 16, 2007
    Location:
    USA
    #24
    I have the 3870 Mac + PC Edition.

    My 4870 is on order from Apple. I'll post here once I actually have it and let everyone know how it works with the 3870, but I'm not expecting any problems.
     
  25. sparkie7 macrumors 68000

    sparkie7

    Joined:
    Oct 17, 2008
    #25
    have you got your 4870 yet.. any update on both cards working?
     

Share This Page