iMac 27" 2011 with eGPU over mPCIe port (EXP GDC)

Discussion in 'iMac' started by miloshov, Jul 25, 2019.

  1. miloshov macrumors newbie


    Jun 28, 2019
    Hello to all.
    I wanted to create this thread since there isn't one anywhere that I found.

    Let's start from the beginning:

    I am YouTuber in making and wanted to create a channel around how-to and other tutorials.
    Since there is not enough money to buy expensive gear from the start I decided to start with old iMac 2011 27", some basic lithing and my iPhone.

    I bought iMac cheep (below 300$) whit stock specs and wanted to upgrade it fully.

    So I added 32GB of RAM, Intel Core i7 2600, and 180 SSD with 500GB HDD in fusion drive for storage.

    Here are the instructions for making fusion drive by them selfs if someone needs it.
    How to make your own Fusion Drive
    It isn't too difficult to make your own version of Apples Fusion Drive, and it can give you a nice speed boost without taking away from storage.

    So the only thing left was GPU. I bought used Radeon HD 6970 2GB for 80$ and flashed Apple ROM on it successfully.

    Instructions for flashing Apple ROM on other brands GPUs:
    SOLVED: What GPU's are compatible with iMac 27" 2011? - iMac Intel 27" EMC 2429
    I used one of the Dell / Alienware 2GB cards. These can still be got for under $200 on eBay. The Apple card is identical in every way except for the firmware. This is the Dell / Alienware card here Grab the Apple ROM file from here: Pay attention to...
    Needed ROM version:
    Apple HD 6970M VBIOS
    2048 MB GDDR5, 680 MHz GPU, 900 MHz Memory

    Done with everything, installed the new GPU started iMac and it was working right away perfectly.
    I run some tests did some video editing and at the end sent machine to sleep.

    Next day after work iMac wouldn't wake up from sleep. I did everything I knew but nothing helped.
    In the end, I switched my old GPU back and the machine worked.

    I tested the card's ROM and foud out that ROM was not there anymore.
    BIOS was empty. Apparently, something was wrong with this GPU and I didn't want to put it back in.

    After all that I found out about EXP GPU and several successful usages on MacBooks and MacBooks Pro.
    Went out bought one for 50$ and started working on it.

    First, I checked if it was working at all. Connected it to my old PC laptop and it is working great.
    Then I connected it all to iMac and came to know that macOS (High Sierra 10.13.6) is not recognizing any GPU I put in (GTX 1050Ti, R9 390 and RX480). If I run Windows on iMac it is working but only on an external display, as it was on the PC Laptop also.

    So what I want to do is making it work in macOS and with internal display.

    Did anyone had any experience with this and any idea how to overcome these issues?

    I found a thread on this forum, but they only managed to get it working on laptops no desktop.
    One guy did but only with nVidia card and on an external display.

    eGPU on MacBook Pro 4,1 and up with PCIe ExpressCard slot
    Hi, Tagan. I don't think there's a step by step guide. What have you already done? And what is your problem? Did you already connect everything? Which...

    If anyone has any idea how to get this working I would be so gratefull, also he/she would be mentioned in my video about this upgrade... :) :)

    Thanks in advance
  2. NodeOfJS macrumors newbie


    Jul 17, 2019
    I think you have to make mac OS found the integrate GPU first, if you can't, then we have nothing to do, this is issue usually found the laptop Doesn't have integrate GPU .
  3. mikehalloran macrumors 68000

    Oct 14, 2018
    The Sillie Con Valley
    eGPU is only available over Thunderbolt. OS 10.13.3 or earlier. You will need a housing to contain the card and it can’t require Thunderbolt 2 — because you are Thunderbolt 1 only. OS 10.13.4/5/6 crippled eGPU over everything except Thunderbolt 3, something that isn’t available on a 2011–2015 iMac.

    A Fusion drive is possible but ridiculous on a 2011. You have 2 SATA III busses and one SATA II bus for the optical drive. There is 0 upside and plenty of downsides of a FD in a 2011.

    Get an SSD and an OWC temp sensor. Install them. Done.

    Make sure you replace the NV RAM battery while in there. Use a CR2032. Your GPU will go nuts when the battery gets low enough and you’ll get all sorts of wrong advice on the problem. With a fresh battery, you’ll eliminate that as a cause. I’m replacing lots of 2011 and 2012 iMac batteries this year.
    --- Post Merged, Jul 25, 2019 ---
    It may well be cheaper to get a low end used 2017 iMac or something from the Refurb Store.
  4. miloshov thread starter macrumors newbie


    Jun 28, 2019
    Hello thanks for replay.
    do you know how can i do that? are there any instuctions?
    --- Post Merged, Jul 26, 2019 ---
    Hi thanks for insights.
    Acctually am not using TB1 for eGPU. If you check my post i am using mPCIe for it.
    It was successfully done by several ppl on mac laptops, but i am having issue with iMac.

    I am not sure that it would be chepper to buy some refurbished 2017 iMac since till now all this cost me below 600$
    and 2017 imac is not below 1500$ or more...
  5. mikehalloran macrumors 68000

    Oct 14, 2018
    The Sillie Con Valley
    I know what you're trying to do.

    mPCIe doesn't exist on the 2011 iMac. Perhaps someone knows a motherboard modification. The 2011 is SATA III and the 2012 Fusion has an mSATA connector unique to that year — that bus is still SATA III.

    It might be done with adapters and knowhow on the 2013 and later but then you're running the Mac on the SATA III bus which slows things down. Again, better to do eGPU through Thunderbolt.
  6. miloshov thread starter macrumors newbie


    Jun 28, 2019
    mPCIe is the port wifi card is using...
  7. mikehalloran macrumors 68000

    Oct 14, 2018
    The Sillie Con Valley
    So... you got it working?
  8. miloshov, Jul 29, 2019
    Last edited: Jul 29, 2019

    miloshov thread starter macrumors newbie


    Jun 28, 2019
    unfortunately not. I have managed to get it working on external display, but the goal is to use iMac's
    beautiful 27" 2K monitor... I am currently working on that...

    That is why I created this thread... to see if someone managed to do that and to share experiences.

    EXP GPU is generally a great brake through item.
    I am currently using it on my older PC laptop and works like a charm.

    Laptop form 2012 running GTA V on max settings with 60-80 fps in 1080p...
  9. JessieComputes macrumors newbie

    Sep 11, 2016
    This works for me without any patching with High Sierra 13.6, but only using an external monitor. The built-in monitor still works, using the iGPU. I use an RX 550 640sp card, which are available quite cheaply. (It needs to be the 640sp version.) It draws only a small amount of power, and drives a 4k 60Hz monitor, and at 1080p, does about 30 fps on the Heaven benchmark. I also tried an Nvidia 1050ti card, but that did not work. I am currently trying to get the eGPU working with Mojave, but am struggling a bit. Of course with Mojave the iGPU doesn't provide acceleration for the built-in screen.

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8 July 25, 2019