5870 and 5770 together?

Discussion in 'Mac Pro' started by RoastingPig, Jun 18, 2015.

  1. RoastingPig, Jun 18, 2015
    Last edited: Jun 18, 2015

    RoastingPig macrumors 68000


    Jul 23, 2012
    Just real quick how would i go about doing this configuration? would i need that mini 6 pin to regular dual 6 pin running to the 5870 and just the other mini 6 pin to the 5770? also is it safe with the tdp?
  2. Tucom macrumors 65816


    Jul 29, 2006
    It's definitely not safe nor feasible without an additional PSU - the 5870 requires dual 6 pins, and the 5770 requires another, single one. That's three when the Pro only has two.

    Are you just trying to get more screens? If so dual 5770's would work effortlessly and provide all the output options of a 5870
  3. Synchro3 macrumors 68000


    Jan 12, 2014
    You could get the power for the 5770 from internal SATA ports.
  4. bax2003 macrumors 6502a


    Dec 25, 2011
    Quick question. What do you need 5770 and 5870 together for ?

    I tried 5870 and 5770 in MP5.1 with one power splitter (6pin to dual 6 pin. ) and that worked for a week. I needed 4 monitors for short time, and that was all hardware I could use at that time.
  5. RoastingPig thread starter macrumors 68000


    Jul 23, 2012
    I have a spare 5770 and I want to use 4 monitors..I bought the splitter.
  6. Wardenski, Jun 20, 2015
    Last edited: Jun 20, 2015

    Wardenski macrumors 6502

    Jan 22, 2012
    I operated an Apple 5770 and a factory overclocked 5870 GB Sapphire Toxic 2GB without issue for 4 years including bootcamp gaming (inlc Crysis 2) with the 5870 using a Mac Pro 2008 Mac Pro. I re-routed power from the spare molex connector in the drive bay to form an 8 pin connector. So thats 6 pin for 5770, 6 pin for 5870 plus the DIY 8 pin.

    In Windows, the 5870 drove the screen. In OSX only the 5770 was operating. The 5770 became frightfully hot though in Windows for some reason despite being "inactive". For powering monitors I can't see any issue. If you were to simultaneously max out both cards at once though perhaps there would be trouble.

    edit: sorry, I misread, I didnt realise you meant splitting the 6 pin (75 W) into dual 6 pin (2 x 75W). It depends I suppose on how much the 5870 draws whilst powering a screen. I read 19W at https://www.techpowerup.com/reviews/ATI/Radeon_HD_5870/28.html
  7. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    For just powering the screen, I can't see any problem. However, technically it may draw up to 200% power from a single 6 pin cable.

    If you want to use splitter. Connect the 1st 6 pin to the 5870, and then split another one to the 5770 and 5870.

    In this case, if the 5770 only power the screen. It won't use too much power. And when the 5870 doing the heavy duty, it still drawing the power from both 6pin sources.

    E.g. The 5870 really draws 75W from one of the 6pin (usually it won't happen unless your workflow is running Furmark). And the 5770 only use 20W for powering the extra screens. It only draws 95W from a single 6pin. Still technically over the limit, but should stay within normal buffer zone (assume 50% buffer for circuit design). And the Mac Pro won't shut itself down. This is a better option then connect both 6pin on the 5870 to a single source, which may draw up to 150W when under load.

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