Pixlas 4.1 Mac Pro mod

Discussion in 'Mac Pro' started by AndreeOnline, Mar 26, 2015.

  1. 666sheep macrumors 68040

    666sheep

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    Poland
    #26
    Put 2 R9 280X and compare numbers ;) Use external PSU for starters. I won't say more because it's not my personal experience, but I don't have any reasons to not to believe what my source said.
     
  2. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    Zürich
    #27
    Just so that I understand you correctly: you are suggesting that a second 280X might improve my real time Resolve rendering even with the Lite version?

    Problem is that we don't have the return rights in Switzerland that many other countries do. I can't buy a gfx card, try it and then return it and get my money back.

    I am currently looking for a DaVinci dongle on Ebay and such. Maybe I get lucky. I don't intend to even pay $500 for it.

    If someone reads this, has a dongle that came with a BMCC or MBPCC, I'd give you $250 if you're not using it.
     
  3. matthewtoney macrumors regular

    matthewtoney

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    Charlotte, NC
    #28
    This is a great thread and a cool PS mod you're doing, but just a reminder to folks - you can run dual 970's without overdoing the power draw on your existing 2 6-pin boosters. (a number of us on here are doing so) Your mod would be awesome for running dual 980's tho or something ever more powerful. :)
     
  4. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    #29
    Yes, I've been keeping my eyes on that development. It's looking good with two 970s.

    I'm not quite sure yet where they land on the price/performance scale, but it should be good I guess. If I had used any CUDA accelerated apps, that would have been my solution. But I'm mostly FCPX and Resolve. The 970s should be good for Resolve, but like my last posts mention: I'll need to get that dongle. With the amount of sudden spending to get this Mac Pro where it needs to get, another $400 for a dongle is sand in the shoes.

    Also, I'm leaning more towards AMD in the Mac, but I have nothing agains Nvidia. I like that the new cards are power efficient.
     
  5. Surrat macrumors 6502

    Surrat

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    #30
    Two 970 on internal cables I think only applies if you are using them strictly for compute, and not video. If you use them for SLI video or just seperate vid cards in OSX for more monitors, I'm 100% sure they will overload the internal boost cables during any 3d video.
     
  6. mikeboss macrumors 65816

    mikeboss

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    #31
    graphics cards are not allowed to pull more than 75W from a single 6-pin auxiliary power connection.
     
  7. Surrat macrumors 6502

    Surrat

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    #32
    Yes, and he's talking about connecting two cards to each 6pin, causing a much higher amp load while doing 3d video. Also, many cards pull more than 75 watts from a 6pin my GTX 770 did that.
     
  8. matthewtoney macrumors regular

    matthewtoney

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    #33
    There's a rather long thread already on here on doing this with a pair of 970's that includes all the data both idle and under heavy load and that just isn't the case - at least with a pair of non-overclocked standard 970's. I'm not going to post all the benchmarks and power readings since they are all contained in that thread, but it is what convinced me that this would work and after doing so I can *also* confirm that regardless of load on the cards I have never seen it pull more than it should from either 6pin connector.
     
  9. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    Zürich
    #34
    PCIe adapter and splice clips have arrived. Had expected CPU/SSD package to arrive today too, but probably tomorrow then.

    I went with 48GB ram and it's already installed.

    I'm glad the PCIe adapter came from China. That means that as soon as I get the CPUs and blade I can install everything up to a point where I have my dual X5690, 1TB SSUBX,R9 280X 3GB and 48GB.

    That is kind of a working core for further expansion. The PSU mod cable has been sent from Hong Kong and will get here eventually.

    OWC SSD sled adapters are also incoming, so I'll probably go with 2x Samsung 1TB 850 EVO in a 2TB RAID internally for 500MB/s.

    I also ordered the new AC Wireless/Bluetooth card hoping to get Handoff working and some better BT reach.
     
  10. mikeboss macrumors 65816

    mikeboss

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    switzerland
    #35
    what cable exactly have you ordered? and where did you order it?

    I prefer the original SSD adapters from Apple (part nr. 922-9629). got them from letec/dataquest for +/- CHF 30.- each.
     
  11. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    #36
    Thanks for the adapter tip—didn't know about that. And I might need more (only ordered two), so that might come in handy.

    Cable was ordered from ModDIY.com and is basically a longer 8 pin open end --> sleeve --> 8 pin split to dual 8 pin PCIe gfx

    This is the cable I started with and modified
     
  12. nigelbb macrumors 65816

    Joined:
    Dec 22, 2012
    #37
    I am sure that you already know this but the $1995 Black Magic Cinema Camera is bundled with a full copy of DaVinci Resolve including the dongle. You may be able to justify buying the camera if you have a need for it. Alternatively you could buy the camera then sell it without Resolve & dongle or find someone else who will sell the software & dongle & keep the camera.
     
  13. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    #38
    Yes, I know. But the BMCC is not high up on my camera list. I'll try to get the stick from someone who wanted the camera but is satisfied with Resolve Lite. $200-300 or so for the stick.
     
  14. benjaprud macrumors member

    Joined:
    Apr 9, 2015
    #39
    Hi, I'm very interested in your results as I plan to do the same kind of mod in my 4.1 > 5.1 MP soon. I've just installed a Titan X in it and it does work well using a 6 to 8 pin adapter but I'd rather tap directly into the PSU for safety and overclocking purposes.

    One thing I've noticed is that under load the PCI and PSU fans run much faster than with my previous 680 (2000 and 1250 RPM v. about 1300 and 1000 with the 680). That makes the MP a bit noisy under GPU load. It seems the PSU and PCI fan speeds are driven by power consumption rather than temperature sensors as under load my PSU runs much cooler than it ever did before.

    I'd be curious about the fan speeds of your setup as if my assumptions are correct, tapping the power directly from the PSU to the GFX card should drive the PCI fan speeds down.
     
  15. mikeboss macrumors 65816

    mikeboss

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    Aug 13, 2009
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    switzerland
    #40
    this is exactly why I'm interested in this mod! I don't want to run software to control the fan-speeds. I also expect the fans to better behave if I'm getting power directly from the PSU.

    yes, the fan speeds are adjusted according to the amps consumed (not temperature controlled).
     
  16. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    #41
    Interesting.

    Well, I'm happy to say that my CPUs arrived today. As of this moment I've got the CPUs and the SSUBX up and running with the adapter.

    I thought I ordered the v1 adapter, and maybe I did. But I had zero issues with bad alignment or such. It was neatly packaged and a perfect fit.

    Still some work to do with moving over hard drives and gfx card.

    First Geekbench tests has it at about 2800 and 31500 so it's the right ballpark.
     
  17. Surrat, Apr 10, 2015
    Last edited: Apr 10, 2015

    Surrat macrumors 6502

    Surrat

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    #42
    I ran the Valley benchmark in both windows 8.1 pro, and yosemite 10.3 tonight. I used iStat for yosemite, and Macs Fan Control for windows. The PSU and PCI fan didnt change speed during the benchmark, they stayed at 600 and 800 rpm. The GTX 680 card fan did speed up and I could hear it during the benchmark. I also saw PSU temperature of 52c max. I'm not sure if this is too hot, I have no idea what safe temps are for a PSU. It could be that when running heavy 3d, like games, I will need to manually speed up the PSU fan a bit to keep things cool. I cranked it up to 2000rpm for a little while and the PSU temp dropped to 36c during Valley.

    It seems the PSU and PCI fans are controlled by the load on the logic board PCIE power taps. Since my setup now isnt using them at all, those fans dont change speed during benchmark or games. Knowing this, if later I get a dual gpu setup, say two 680 or two 9xx, I will run one logic board tap to each card, and with a splitter run the other two plugs to my 6 pin power tap.

    Something I wanted to point out, the power cable I used in this mod, is very high quality, it came with a 850 watt Seasonic power supply from my previous gaming pc. Its 16guage wire. According to specs for PCIE taps, the weak point is the molex plug pins. There are 3 grades of them. The weakest is rated for about 192 watts. Now, remember, the proper spec for a 75watt pcie tap is that there are only TWO power wires, not three. Which means 96 watts per wire is max safe with the low end pins. Meaning my 16guage cable directly connected to the PSU 12v bus, should be good for 96 watts x 3. I'm not worried about splitting it into two 75 watt 6 pin cables, or even two 150 watt 8pin cables.

    Excellent description of PCIE power cables and ratings is here:
    http://www.tomshardware.com/reviews/power-supply-specifications-atx-reference,3061-12.html
     
  18. benjaprud macrumors member

    Joined:
    Apr 9, 2015
    #43
    Thanks. I've ordered the cable for the PSU mod. I'll be using a 45 cm PCIe 8 pin extension cable from which I will cut one end to solder the wires under the PCB.

    One last thing i'd like to be sure of before starting is where do you connect the sense pins. I've read somewhere else that they're connected to the ground but the guy who said that didn't try the mod himself.
     
  19. Surrat macrumors 6502

    Surrat

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    #44
    We just ran the 'sense' pins to ground. I never have seen any info saying they were not ground.
     
  20. JamietheMac macrumors member

    JamietheMac

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    Sep 5, 2010
    Location:
    Scotland
    #45
    Why do you de-cap the cpus?

    is it a contact thing with the Coolers

    is it easy enough to pop them off yourself

    any guides to doing this?
     
  21. AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    Zürich
    #46
    Following best practice I guess. These CPU swaps have been done for a long time and people have tried both with and without. The 2009 dual CPU was de-lidded from factory and there is a thin spacer as well.

    Using a lid would seat the heatsink a little higher up. It would still fit in the Mac Pro but there is also a connector (probably for the fan) that gets connected as the heatsink is screwed down onto the CPU.

    But like I said, people have had success without de-lidding to. I just didn't want to introduce that as an additional element.
     
  22. AndreeOnline, Apr 17, 2015
    Last edited: Apr 17, 2015

    AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    #47
    I got my PSU mod cable today and I couldn't resist installing it.

    The mod has been installed into my 5.1 single CPU box with an Apple 5870, since that is my original Mac Pro in good condition. I will move all of my "new" dual CPU Mac Pro over to that case since the 4.1 I got is to banged up for my taste (scratches and so on).

    The first test, running the 5870 from my modded cable ONLY (no boosters) was successful.

    My original post has been UPDATED with a few images and some notes.
     
  23. Surrat macrumors 6502

    Surrat

    Joined:
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    #48
    Well, this sure looks easier than what we did on mine... hehe.
    I would remove the optical carrier, and then run a heavy benchmark like Heaven or Valley, and while its running, reach in and feel those splicing clips you used, see if any of them heat up, or are warm. If they stay cool, I would guess your home free.
     
  24. AndreeOnline, Apr 17, 2015
    Last edited: Apr 17, 2015

    AndreeOnline thread starter macrumors 6502

    AndreeOnline

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    #49
    That is how I tested the mod when I first started it. I let it run Valley and FurMark for quite some time. Mind you, this was just with the 5870 (but it was powered solely from the mod cables).

    I didn't want to touch the cables when everything was running, but immediately afterwards I felt all the cables (and PSU) and nothing was even remotely warm.

    I will need to REALLY put it to the test with dual cards at some point, but I consider the mod successful.

    When I finally closed the case I actually managed to get the guard plate attached with the left screw, so the mod is now very clean. With a longer screw on the right side I could have screwed it on there as well, but it was already firmly in place.
     
  25. m3rob macrumors member

    Joined:
    Dec 28, 2010
    #50
    AndreeOnline,

    Your modification to tap into the power supply looks great! How would I go about ordering the parts so I can run this on my system? Is it all custom work to get the cables?

    Also, a bit of a newbie question, if I wanted to power a card with 2-6 pins instead of 8 is it as easy as just not using the extra 2 pins that are partially attached to the cable?

    Thanks for posting your findings!
     

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