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

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

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(@milos_hovjecki)
New Member
Joined: 4 weeks ago
 

Hello to all,

I am new to this site and forum so I would like to say sorry if some rules are broken by my side.

 

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 XS.

 

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.

https://www.macworld.com/article/2014011/how-to-make-your-own-fusion-drive.html

 

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:

https://www.ifixit.com/Answers/View/296157/What+GP U's+are+compatible+with+iMac+27%22+2011#answer420333

Needed ROM version:

https://www.techpowerup.com/vgabios/109915/apple-hd6970m-2048-110128

 

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 would not wake up from sleep. I did everything I knew but nothing helped.

In the end, I switched old GPU back in and the machine worked. So 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 cam 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 one thread om macrumors, but they only managed to get it working on laptops and with GTX card but only with an external display.

https://forums.macrumors.com/threads/egpu-on-macbook-pro-4-1-and-up-with-pcie-expresscard-slot.2135898/page-8

 

Thank you in advance.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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Wiktorion
(@wiktorion)
Active Member
Joined: 4 weeks ago
 

I had this exact idea for my old 2011 A1312 iMac. After doing some tests I realized it would not be worth the effort.

You would need to step down to Thunderbolt 1 which has a very low bandwidth. To add to this, if you want to accelerate the internal display you would have even lower bandwidth since the data goes both ways in the cable.

The one-way bandwidth is literally a tenth of the PCI-e bandwidth that the A1312 iMac enjoys. As you know you can put any MXM form factor card in there. Install nVidia web drivers for High Sierra and you can install a lot of different cards.
I installed an MXM nVidia GTX 765m in mine. It did require some modifying of the heatsink and drilling larger mounting holes in the card but that was it. This solution is in my mind far superior and cheaper in comparison to getting an eGPU, convert it to Thunderbolt 1 and accelerate the internal display. This is not accounting for any issues the eGPU will bring, like conflict with the internal graphics card or similar.

My advice with this specific machine is to save your money and time and just keep trying with MXM cards. This solution is more elegant and efficient in almost all ways. There are examples of people getting fairly advanced cards working like the GTX9xxM and similar.

Macbook Air 2018 + AGB RX570


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(@milos_hovjecki)
New Member
Joined: 4 weeks ago
 

Hi @wiktorion,
thanks for the update. Actually I wanted to do this upgrade over mPCIe port, not over TB 1.

I know that TB 1 is not fast enough and it would be a pain, that is why I used EXP GDC

Many ppl did it with their mac laptops but I cannot do it on mac desktop.

So I am interested to know what is the difference. 

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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Wiktorion
(@wiktorion)
Active Member
Joined: 4 weeks ago
 

@milos_hovjecki

Okay! I'm sorry, I misunderstood completely!

It seems like an interesting solution, I googled around and found an adapter. The bandwidth should allow it to work well in theory as long as the system recognizes the card. It seems that mPCIe is single lane though? Or can it be expanded?

Macbook Air 2018 + AGB RX570


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(@milos_hovjecki)
New Member
Joined: 4 weeks ago
 

@wiktorion

Not really sure about that. 🙂
Currently i think that newer AMD cards are having issues with iMac somehow.
Also. nVidia is working only with external display. 

I am currently serching for god older GPU both AMD and nVidia. 
To try with them. If nothing i will definitelly sell iMac and buy something newer. 🙂

This post was modified 3 weeks ago

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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ericthetrip
(@ericthetrip)
New Member
Joined: 2 weeks ago
 

@wiktorion

Hi there,

So you need an external monitor to use an egpu in a 2011 Imac via Thunderbolt 1 port?
I've recently bought a BizonBox3 on ebay, it was a good deal and I've wanted to use an egpu on my Mid 2011 27" Imac and on my Mid 2012 13" macbook.
I'm a videographer and I do ok with my 2012 Macbook pro and 2011 Imac, but I really need extra gpu power.
The portability of a egpu would be great, but an external monitor would not, so is there any other workaround?

Thank you so much

This post was modified 2 weeks ago

27" mid 2011 Imac i7 3.4 AMD Radeon HD 6970M 2GB 32GB RAM running macos High Sierra 10.13.6
13" mid 2012 Macbook Pro i7 2.9 Intel HD Graphics 4000 16GB RAM running macos Mojave 10.14.6
EGPU BizonBox3 Thunderbolt 3 to Thunderbolt 2 Adapter Radeon RX 580 8GB


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