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Beginning the process of doing an upgrade to an iMac 10,1 from gt 9400 to a firepro m5100 I scored for cheap. I'm up to high Sierra with the intention of upgrading to Monterey and beyond. Anyone attempt this specific GPU before or have any idea what I'm getting myself into software-wise? I ended up with the red Dell Elpidia RAM card.
 
Black Screen: After complete installation of the iMac the internal LCD can stay black, only three status LED light up. This is the black screen software issue. Normally you can get around it (temporarily) by pressing alt/option on boot.

If this does not fix your problem sell everything you have.

Lol, I was in such a bad mood when I wrote that comment last night because it felt like I wasted money.

I'm not actually going to sell it, because it's still perfectly usable with an external display. I've read the 1st page multiple times trying to figure everything out from there, but at this point, I'll take a month-long break from this project and try to enjoy using it as it is. I have a gut feeling I missed a small step.
 
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Beginning the process of doing an upgrade to an iMac 10,1 from gt 9400 to a firepro m5100 I scored for cheap. I'm up to high Sierra with the intention of upgrading to Monterey and beyond. Anyone attempt this specific GPU before or have any idea what I'm getting myself into software-wise? I ended up with the red Dell Elpidia RAM card.

I would call you the genie if you could ever pull out this successfully.
In reality, you are facing a hardware issue, not a software issue.
What you are getting yourself into is a "Open case, check-up, give-up, close case" scenario.
 
Beginning the process of doing an upgrade to an iMac 10,1 from gt 9400 to a firepro m5100 I scored for cheap. I'm up to high Sierra with the intention of upgrading to Monterey and beyond. Anyone attempt this specific GPU before or have any idea what I'm getting myself into software-wise? I ended up with the red Dell Elpidia RAM card.
I believe that this upgrade may not be possible for your specific model of iMac --because of the GT9400 --I don't recall anyone having success upgrading this particular model of GPU in their iMac before. If you do in fact have the model of 21" 2009 iMac that doesn't use a GT9400, then there is still hope.

See this post: https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/post-29767933
@Ausdauersportler said EDIT: There exist iMac10,1 models without MXM slots and an internal GT9400 GPU. You cannot modify those models. Check carefully.
 
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I believe that this upgrade may not be possible for your specific model of iMac --because of the GT9400 --I don't recall anyone having success upgrading this particular model of GPU in their iMac before. If you do in fact have the model of 21" 2009 iMac that doesn't use a GT9400, then there is still hope.

See this post: https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/post-29767933
Welp, looks like I might be returning the GPU then. A friend has an iMac 27" with a dead PSU so I might see about giving him this with the upgraded components and giving that one a stab, or try Monterey via non-Metal GPU acceleration. So well for this one though, will still take a look and see if it's soldered in or not just in case.

Edit: Just thought I’d mention that my only use case for the computer is a Universal control/Airplay to Mac monitor for school. I already have my iPad pro but absolutely despise using MS Office suite on it and would like something I can quickly and easily use for a light-ish workload.
 
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Welp, looks like I might be returning the GPU then. A friend has an iMac 27" with a dead PSU so I might see about giving him this with the upgraded components and giving that one a stab, or try Monterey via non-Metal GPU acceleration. So well for this one though, will still take a look and see if it's soldered in or not just in case.

Edit: Just thought I’d mention that my only use case for the computer is a Universal control/Airplay to Mac monitor for school. I already have my iPad pro but absolutely despise using MS Office suite on it and would like something I can quickly and easily use for a light-ish workload.
You should check the hardware needed for UC and AirPlay to Mac - surely it needs a WiFI/BT upgrade of your iMac. All about Monterey on this thread (reading the first post will help, same story as here) or on the OCLP Github page.
 
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Welp.... received the display replacement today and still no 4th LED after plugging it in. I really thought it would work because I'm booting with Opencore.

Honestly? **** it I give up. Just gonna sell the 2011. Piece of junk anyways.
I had similar issues when I tried a GTX 880m ages ago, couldn’t get the screen to respond even with the original gpu back in. I’m not sure what fixed it but I remember doing multiple pram resets, like 10 or more in a row and also removed the logic board battery and did more resets and removed the ram etc.

Eventually I got the lcd to respond but not with the 880m

The 880m then got put in a 2009 where it also had black screen however the screen lit up after the Mac was woken from sleep, then the problem never returned but the card died after my son hammered it playing RUST.
 
So I should too? I have the same issue..
iMac 2011: Some NVIDIA GPU may not run well in your 27 Mid 2011 iMac. We have reports of GTX880M, K3000M, K3100M, K4100M, K5000M which all run only without the internal LCD connected. As soon as you connect the LCD the system refuses to boot or ends up in boot chime loop. Sometimes the same error is related to connecting and disconnecting the single internal SSD. Meanwhile we believe the root cause are address conflicts on the SMBUS caused either by the GPU or some IC on the card connected to the SMBUS delivering thermal data. Sometimes you can visualize such problems with tools like HW Monitor. If you find additional weird temperature readings you might have such a card. No software solution possible! Lately on user made this modification and got his K3100M working.
 
Hi Mac fans!

I'm having some trouble with my 27" iMac mid 2011, and an AMD WX 4130 (DELL) that I flashed with the described rom in the table. I've added my original rom from the forum (identical to mine)) so anyone can take a look at what might be the cause of getting a "black screen".

Here's my timeline so far and why IT DID WORK at first on a 2nd monitor, without even flashing the card tbw.

My GPU broke down so I had to replace it, and opted for a 4130 that was available in my neighbourhood (not china). It is a Dell card, and I did the special install perfectly (copper plates and all), and when I booted the iMac I didn't get a screen...

Then I tried to see if it would project on a 2nd monitor and it did! I saw my good-old login and everything worked as normal, except it doesn't show on the 1st monitor. Knowing that I needed to flash the card in Linux, I installed Linux on a spare HDD and swapped it with the OSX SSD.

Linux also booted on the 2nd minotor, and not the 1st. Like with the iMac.

Before I wanted to do any flashing of the card, I tried a PRAM reset... This worked but didn't show OSX on the 2nd monitor anymore, and also not the first. (!! this is an important moment, you'll see later). The card wouldn't work at all now, so I forced myself to flash the card in Linux now.

I flashed the card with the WX-4130_GOP.rom and rebooted. Now both screens work! Linux shows both monitors working and that the flash was succesfull. That's one less worry! Now for OSX...

It boots but it doesn't show any monitor. Even after a 2nd PRAM reset there is no change. And this is where I tried to the old rom back, and retry. But it just put me back into the state before flashing; the 2nd monitor worked in Linux, not OSX anymore.

CONCLUSION:
When you put in a new AMD card, and you can get it to work without flashing the card or do a PRAM reset, then don't do the PRAM reset because I think there is one of two things going on; it already has the right state to operate, just needs to be flashed without doing the PRAM reset. You can always do a PRAM reset, right? So don't. It worked without it on my 2nd monitor.

My other conclusion is that it must be something to do with the motherboard configuration and OSX, and that by doing a reset it looks again and "kicks" you. The card simply works when you boot linux, so it's not a hardware issue (is it?). Anyone know of kext that I might need for this? I can access the OSX SSD through Linux (dual boot) to put the files in OSX, or to configure some plist.

EXPERIMENT:
Now that I might be on the hunt for the right culprit, the PRAM reset that doesn't need to happen, I also thought of a slipstream-solution;
1. Take out the WX4130 and replace it with a classic iMac GPU (the ********* you can find)
2. Once you have it installed, perform the PRAM reset so iMac looks again at your official GPU
3. Once done, replace the surrogate with your flashed WX4130 GPU and not doing a PRAM reset

This experiment is something that I will investigate further, as for now I think it is the only solution that will "work" as the GPU was recognized by High Sierra before the PRAM reset. In theory that would "undo" the block the way I see it but that's all experimental.

SUGGESTIONS:

Any help would be greatly appreciated for me and others that are facing the same issues with AMD GPU's, as they are much trickier than NVIDIA GPU's.
If you're ever going to upgrade your iMac, and you're new to building PC's and such, please get an NVidia card as there are far more people and videos who can help you out.

Anyone know of kext that I might need for this problem? I can access the OSX SSD through Linux (dual boot) to put the files in OSX, or to configure some plist. You can also reach me at askgu.us


my model: iMac 27 Mid 2011 WX4130 i7-2600k 16GB RAM High Sierra
 

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Hi Mac fans!

I'm having some trouble with my 27" iMac mid 2011, and an AMD WX 4130 (DELL) that I flashed with the described rom in the table. I've added my original rom from the forum (identical to mine)) so anyone can take a look at what might be the cause of getting a "black screen".

Here's my timeline so far and why IT DID WORK at first on a 2nd monitor, without even flashing the card tbw.

My GPU broke down so I had to replace it, and opted for a 4130 that was available in my neighbourhood (not china). It is a Dell card, and I did the special install perfectly (copper plates and all), and when I booted the iMac I didn't get a screen...

Then I tried to see if it would project on a 2nd monitor and it did! I saw my good-old login and everything worked as normal, except it doesn't show on the 1st monitor. Knowing that I needed to flash the card in Linux, I installed Linux on a spare HDD and swapped it with the OSX SSD.

Linux also booted on the 2nd minotor, and not the 1st. Like with the iMac.

Before I wanted to do any flashing of the card, I tried a PRAM reset... This worked but didn't show OSX on the 2nd monitor anymore, and also not the first. (!! this is an important moment, you'll see later). The card wouldn't work at all now, so I forced myself to flash the card in Linux now.

I flashed the card with the WX-4130_GOP.rom and rebooted. Now both screens work! Linux shows both monitors working and that the flash was succesfull. That's one less worry! Now for OSX...

It boots but it doesn't show any monitor. Even after a 2nd PRAM reset there is no change. And this is where I tried to the old rom back, and retry. But it just put me back into the state before flashing; the 2nd monitor worked in Linux, not OSX anymore.

CONCLUSION:
When you put in a new AMD card, and you can get it to work without flashing the card or do a PRAM reset, then don't do the PRAM reset because I think there is one of two things going on; it already has the right state to operate, just needs to be flashed without doing the PRAM reset. You can always do a PRAM reset, right? So don't. It worked without it on my 2nd monitor.

My other conclusion is that it must be something to do with the motherboard configuration and OSX, and that by doing a reset it looks again and "kicks" you. The card simply works when you boot linux, so it's not a hardware issue (is it?). Anyone know of kext that I might need for this? I can access the OSX SSD through Linux (dual boot) to put the files in OSX, or to configure some plist.

EXPERIMENT:
Now that I might be on the hunt for the right culprit, the PRAM reset that doesn't need to happen, I also thought of a slipstream-solution;
1. Take out the WX4130 and replace it with a classic iMac GPU (the ********* you can find)
2. Once you have it installed, perform the PRAM reset so iMac looks again at your official GPU
3. Once done, replace the surrogate with your flashed WX4130 GPU and not doing a PRAM reset

This experiment is something that I will investigate further, as for now I think it is the only solution that will "work" as the GPU was recognized by High Sierra before the PRAM reset. In theory that would "undo" the block the way I see it but that's all experimental.

SUGGESTIONS:

Any help would be greatly appreciated for me and others that are facing the same issues with AMD GPU's, as they are much trickier than NVIDIA GPU's.
If you're ever going to upgrade your iMac, and you're new to building PC's and such, please get an NVidia card as there are far more people and videos who can help you out.

Anyone know of kext that I might need for this problem? I can access the OSX SSD through Linux (dual boot) to put the files in OSX, or to configure some plist. You can also reach me at askgu.us


my model: iMac 27 Mid 2011 WX4130 i7-2600k 16GB RAM High Sierra
My recommendation is to avoid using High Sierra with those newer AMD cards!
Mojave or later should work better.

Please please please don't ever ever again report any problem with High Sierra and those later AMD cards (Polaris or GCN 4.0) - simply stay away from that OS version!
 
Hello all,
I just wanted to weigh in with my findings on the GPU upgrades on the 2009-2011 IMacs
I first started by upgrading a 27 inch 2,66ghz i5 2009 IMac with a ''new'' videocard since the 4850 the came with it broke in may 2021. I thought while I was in there I might as well upgrade the cpu to a i7 860.
After a lot of searching I came across a Quadro K4000M for only 50 Eur, I snapped this up and the experiment began.
I first installed the i7 860 and tested the machine, this worked flawlessly so on to the gpu. My IMac came with the 2 pipe cooler but it thought this would be fine for now. I followed the instructions and installed the card without using the dremmel tool since it fit fine without using it. After installing the card I booted up a copy of high Sierra, and well, It worked as expected, full brightness and no bootscreen but acceleration and full functionality. After this I flashed the K4000M using the linux usb stick method, what a breeze!. Instructions were very clear and easy to follow. after about half a hour I had a working flashed K4000M in my system. Reading about the 3-pipe heatsink I thought I would stress the card using a costum fan preset based on gpu heatsink (60-75 Celsius max) I booted up windows and played gat 5 for about 2 hours, the card stayed under 75 Celsius with decent fan speeds!. Im thinking that for the not extremely high end MXM-B cards the 2-pipe big heatsink should suffice if the proper fan control is used. I have been using the machine for about a year now and it is such a great machine! It is on Monterey right now with the latest updates and everything works great.

So, recently I found a 27 inch 2011 IMac with the 3,4Ghz i7 with a defective 6970M for only 50 eur. After my succes on my older IMac I was excited to try it on this IMac as well. I had a K3000M lying around which I flashed a while ago on a 2011 21.5 inch IMac, for testing purposes. So out was the 6970M and in was the K3000M, and again after following all the steps in this wiki (except the dremmeling of the heatsink) it works great!. Kept the original 2TB HDD in place and added a 250GB SSD in the ODD bay, temps are looking fine and performance is really good, about 30% less gpu power then the K4000M but im not pulling the machines apart again for that swap. the 2011 requires full disassembly of the motherboard for a gpu swap so it is kind of tedious.

I wanted to say thank you to all people who have contributed to this thread with the useful information and ROMS! you have breathed completely new life in machines that still got good potential!

In the future id love to put a newer AMD card in the 2011 27 inch, but reading about them makes it seem as most of them break the sleep function in these machines, which is really a bummer. for now the K3000M will do just fine in Monterey.
 
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Hi Mac fans!

I'm having some trouble with my 27" iMac mid 2011, and an AMD WX 4130 (DELL) that I flashed with the described rom in the table. I've added my original rom from the forum (identical to mine)) so anyone can take a look at what might be the cause of getting a "black screen".

Here's my timeline so far and why IT DID WORK at first on a 2nd monitor, without even flashing the card tbw.

My GPU broke down so I had to replace it, and opted for a 4130 that was available in my neighbourhood (not china). It is a Dell card, and I did the special install perfectly (copper plates and all), and when I booted the iMac I didn't get a screen...

Then I tried to see if it would project on a 2nd monitor and it did! I saw my good-old login and everything worked as normal, except it doesn't show on the 1st monitor. Knowing that I needed to flash the card in Linux, I installed Linux on a spare HDD and swapped it with the OSX SSD.

Linux also booted on the 2nd minotor, and not the 1st. Like with the iMac.

Before I wanted to do any flashing of the card, I tried a PRAM reset... This worked but didn't show OSX on the 2nd monitor anymore, and also not the first. (!! this is an important moment, you'll see later). The card wouldn't work at all now, so I forced myself to flash the card in Linux now.

I flashed the card with the WX-4130_GOP.rom and rebooted. Now both screens work! Linux shows both monitors working and that the flash was succesfull. That's one less worry! Now for OSX...

It boots but it doesn't show any monitor. Even after a 2nd PRAM reset there is no change. And this is where I tried to the old rom back, and retry. But it just put me back into the state before flashing; the 2nd monitor worked in Linux, not OSX anymore.

CONCLUSION:
When you put in a new AMD card, and you can get it to work without flashing the card or do a PRAM reset, then don't do the PRAM reset because I think there is one of two things going on; it already has the right state to operate, just needs to be flashed without doing the PRAM reset. You can always do a PRAM reset, right? So don't. It worked without it on my 2nd monitor.

My other conclusion is that it must be something to do with the motherboard configuration and OSX, and that by doing a reset it looks again and "kicks" you. The card simply works when you boot linux, so it's not a hardware issue (is it?). Anyone know of kext that I might need for this? I can access the OSX SSD through Linux (dual boot) to put the files in OSX, or to configure some plist.

EXPERIMENT:
Now that I might be on the hunt for the right culprit, the PRAM reset that doesn't need to happen, I also thought of a slipstream-solution;
1. Take out the WX4130 and replace it with a classic iMac GPU (the ********* you can find)
2. Once you have it installed, perform the PRAM reset so iMac looks again at your official GPU
3. Once done, replace the surrogate with your flashed WX4130 GPU and not doing a PRAM reset

This experiment is something that I will investigate further, as for now I think it is the only solution that will "work" as the GPU was recognized by High Sierra before the PRAM reset. In theory that would "undo" the block the way I see it but that's all experimental.

SUGGESTIONS:

Any help would be greatly appreciated for me and others that are facing the same issues with AMD GPU's, as they are much trickier than NVIDIA GPU's.
If you're ever going to upgrade your iMac, and you're new to building PC's and such, please get an NVidia card as there are far more people and videos who can help you out.

Anyone know of kext that I might need for this problem? I can access the OSX SSD through Linux (dual boot) to put the files in OSX, or to configure some plist. You can also reach me at askgu.us


my model: iMac 27 Mid 2011 WX4130 i7-2600k 16GB RAM High Sierra
You may better put your Mac configuration in your Signature so that any potential helper can see it with every message you posted.

This is not a plug-&-play solution and often requires more communication among forum members than you thought.

I have tried a few Dell WX4130 in my iMac 2010 and the 2nd external monitor always works even without flashing.
That helps to flash the card with the posted vBIOS with a Linux USB thumb drive.

I agree with internetzel than DON'T use High Sierra with these newer AMD GPU. I have 3 internal SSDs each of different macOS (Catalina, BigSur, Monterey) and the Catalina drive is initially High Sierra that has caused me many troubles from slow running, crashing, to corruption of my other drives. So, prepare yourself a Catalina (or even newer OS) USB thumb drive to install to your internal drive. Even if the installation of Catalina or later macOS is successful, the GOP vBIOS won't give you a boot screen on your internal display panel. It will remain black until the macOS system is fully loaded with the graphic driver to show you the login screen. However, that can be overcomed with OCLP Bootpicker if you install OCLP onto your internal disk or boot from the OCLP on either a SD card, USB thumb drive connected to internal USB slot, or CD/DVD disk from your DVD drive that is cleverly devised by Ausdauersportler.

PRAM reset may or may not be the culprit. In the initial experimentation, you really need many PRAM reset to clear the NVRAM and prepare for installation of OCLP, or after changing the GPU. Also whenever you update your OCLP, you need PRAM reset to clear all flags for the new OCLP Bootpicker to properly work. Thus, PRAM reset would not brick your Mac or GPU. But you may need to do PRAM reset consecutively 3 times to make sure the stored NVRAM content is adequately cleared. I have done many PRAM reset in my iMac with a flashed RX480 without any issue. While the iMac 2011 seems to be a little picky on AMD cards, many have reported success in the database. Your WX4130 also seems to be working. The vBIOS posted is confirmed to be working by many. We all have great experience with OCLP. And you have the skill to manage your hardware. So, if your internal LCD panel or connection cable isn't broken (since you can at one time show the macOS on it), just follow all the steps again with a new OS. Stay away from High Sierra.

You are near the finishing line. Add oil.
 
I just started my own project and am running into an issue.

I installed oclp over a high sierra install. Holding option on reboot just gives me a grey screen. I have no other installs, just a broken internal hdd and odd. I am wondering if maybe the boot picker only shows up if I have a second install.
 
My recommendation is to avoid using High Sierra with those newer AMD cards!
Mojave or later should work better.

Please please please don't ever ever again report any problem with High Sierra and those later AMD cards (Polaris or GCN 4.0) - simply stay away from that OS version!
THank you for your advise, it is recommended that you have a few iMac upgrades under your belt to do any AMD cards maybe. I have the technical chops to manage and configure a custom build PC, but not that many people do initially. This is my first iMac, I used to run a Hackintosh up until a few years ago.
 
I just started my own project and am running into an issue.

I installed oclp over a high sierra install. Holding option on reboot just gives me a grey screen. I have no other installs, just a broken internal hdd and odd. I am wondering if maybe the boot picker only shows up if I have a second install.
I remember that it says you need to disable some OS-check (flag) if you wish to run High Sierra in OC, since it doesn't support older versions of OSX before 10.14 (High Sieraa is 10.13). Check the original post on how to do that, but maybe it's already to late since you can't see anything.
 
You may better put your Mac configuration in your Signature so that any potential helper can see it with every message you posted.

This is not a plug-&-play solution and often requires more communication among forum members than you thought.

I have tried a few Dell WX4130 in my iMac 2010 and the 2nd external monitor always works even without flashing.
That helps to flash the card with the posted vBIOS with a Linux USB thumb drive.

I agree with internetzel than DON'T use High Sierra with these newer AMD GPU. I have 3 internal SSDs each of different macOS (Catalina, BigSur, Monterey) and the Catalina drive is initially High Sierra that has caused me many troubles from slow running, crashing, to corruption of my other drives. So, prepare yourself a Catalina (or even newer OS) USB thumb drive to install to your internal drive. Even if the installation of Catalina or later macOS is successful, the GOP vBIOS won't give you a boot screen on your internal display panel. It will remain black until the macOS system is fully loaded with the graphic driver to show you the login screen. However, that can be overcomed with OCLP Bootpicker if you install OCLP onto your internal disk or boot from the OCLP on either a SD card, USB thumb drive connected to internal USB slot, or CD/DVD disk from your DVD drive that is cleverly devised by Ausdauersportler.

PRAM reset may or may not be the culprit. In the initial experimentation, you really need many PRAM reset to clear the NVRAM and prepare for installation of OCLP, or after changing the GPU. Also whenever you update your OCLP, you need PRAM reset to clear all flags for the new OCLP Bootpicker to properly work. Thus, PRAM reset would not brick your Mac or GPU. But you may need to do PRAM reset consecutively 3 times to make sure the stored NVRAM content is adequately cleared. I have done many PRAM reset in my iMac with a flashed RX480 without any issue. While the iMac 2011 seems to be a little picky on AMD cards, many have reported success in the database. Your WX4130 also seems to be working. The vBIOS posted is confirmed to be working by many. We all have great experience with OCLP. And you have the skill to manage your hardware. So, if your internal LCD panel or connection cable isn't broken (since you can at one time show the macOS on it), just follow all the steps again with a new OS. Stay away from High Sierra.

You are near the finishing line. Add oil.
Thank you so much for the encouraging words! I luckily have a 21,5 iMac that I found on the street to make me a OC bootable USB or alike once I get the cable that was broken replaced. I think I have plenty of options to go from here, it's just picking "the best" route.

I'm still puzzled about one thing; how can you run OCLP bootpicker if you can't see what's loaded? I managed to "blind select" a dual boot I believe, and the way I see it is you have to somehow select it on boot while holding ALT to select the thumb-drive. How I do it now is by simply swapping out hard-drives on the main SATA-port (I have two installed) so it loads either Linux or OSX.

Since I prefer a dual boot, and want to choose boot-disks, I'm most certainly using OC in the future. So I better bet all-in on that horse.

But what puzzles me about your explenation is that I need to do this Catalina install "blindly" on my iMac, but how can I see what I'm doing?

It's a GUI-based install, I can't know what keys to press upfront (unless you have a "map"). Or will it work on my 2nd monitor because of OC somehow? That part leaves me a bit clueless on how to approach that part.

I have thought about installing it on a hard-drive inside my 21,5" and put that drive into the 27", but from my experience this doesn't work because I did that trick with my mom's iMac that I gave her this Xmas. It will result in the fact you can't put a SSD with OSX from a 21,5" from 2011, inside a 27" from 2010. It just shows the white boot-screen and doesn't load the OS. What did work was putting the 27" from 2010, inside a 21,5" from 2011 without any trouble or post install issues.

However... Since OC creates it's own kind of "spoofing", this issue might not at all be present since it's already faked to make the OS think it's newer hardware. So does my "swaploading" tactic sound like a plan to you all, or has anyone ever considered or tried it? Maybe that's for good reasons nobody did, but these things are also kind of invengineering your own solutions.
 
Thank you so much for the encouraging words! I luckily have a 21,5 iMac that I found on the street to make me a OC bootable USB or alike once I get the cable that was broken replaced. I think I have plenty of options to go from here, it's just picking "the best" route.

I'm still puzzled about one thing; how can you run OCLP bootpicker if you can't see what's loaded? I managed to "blind select" a dual boot I believe, and the way I see it is you have to somehow select it on boot while holding ALT to select the thumb-drive. How I do it now is by simply swapping out hard-drives on the main SATA-port (I have two installed) so it loads either Linux or OSX.

Since I prefer a dual boot, and want to choose boot-disks, I'm most certainly using OC in the future. So I better bet all-in on that horse.

But what puzzles me about your explenation is that I need to do this Catalina install "blindly" on my iMac, but how can I see what I'm doing?

It's a GUI-based install, I can't know what keys to press upfront (unless you have a "map"). Or will it work on my 2nd monitor because of OC somehow? That part leaves me a bit clueless on how to approach that part.

I have thought about installing it on a hard-drive inside my 21,5" and put that drive into the 27", but from my experience this doesn't work because I did that trick with my mom's iMac that I gave her this Xmas. It will result in the fact you can't put a SSD with OSX from a 21,5" from 2011, inside a 27" from 2010. It just shows the white boot-screen and doesn't load the OS. What did work was putting the 27" from 2010, inside a 21,5" from 2011 without any trouble or post install issues.

However... Since OC creates it's own kind of "spoofing", this issue might not at all be present since it's already faked to make the OS think it's newer hardware. So does my "swaploading" tactic sound like a plan to you all, or has anyone ever considered or tried it? Maybe that's for good reasons nobody did, but these things are also kind of invengineering your own solutions.
With the GOP AMD vBIOS, the build-in Apple BootPicker does not work (pressing Option key at restart).
The only way to choose bootable attached drives is via the OCLP Bootpicker (pressing Control key at restart).

Now if your iMac works with the new AMD GPU (with or without flashing), you can do all these preparation on the second monitor under macOS if your old OS still works, or putting back your old working AMD card to get back to your old OS and prepare everything. It would help of course if you got another Mac a/v. Note that OCLP is hardware-specific. However, as I said, the easiest way is to create an OCLP bootable CD/DVD if you haven't dismounted your internal DVD drive. Read post 1 for the details. Just press the C key during restart to boot from CD/DVD, then you will have access to the OCLP BootPicker.
https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/post-30197513

Another more winding route is to install Catalina with DOSDude1's Catalina Patcher with your old working AMD card on your internal LCD panel, or your new AMD GPU on your second ext monitor. Then you may create the proper version of OLCP (which is hardware specific with regard to the GPU you swap in) and update your OCLP. Putting this updated OCLP on either a SD card, CD/DVD or USB thumb drive, you can proceed to re-install your macOS.
 
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Put the ssd back in and boot up then test your ethernet port on the Mac to make sure its working also test the linux usb stick in all you USB ports, I have had Macs with faulty ethernet port (use and adapter to get around this) I also have Macs with dead USB ports or ports that have power but not data. Once you verify that the Ethernet port and USB port is working you should be good to go.
I checked all the USB ports and they all work normally. iMac is permanently connected with modem through the Ethernet port so it also work. The Linux USB stick successfully runs on another iMac. I checked the modem and it normally recognizes other devices on the network. I see no other solution than to try @jowaju installer package for Windows 7. Is there a step by step tutorial for this GPU card flashing method?
Thx
 
I checked all the USB ports and they all work normally. iMac is permanently connected with modem through the Ethernet port so it also work. The Linux USB stick successfully runs on another iMac. I checked the modem and it normally recognizes other devices on the network. I see no other solution than to try @jowaju installer package for Windows 7. Is there a step by step tutorial for this GPU card flashing method?
Thx

Yes, there are 2 posts, with links hidden somewhere in post #1.
 
I read all the post, saw many videos on YT on this topic... and i decided to start this adventure...

I'm going to write my experience but i need a little bit of your help, to complete tis adventure...

This is my 27" iMac (with CPU successfully changed i5->i7): Mid 2011 - 3,4 GHz Intel Core i7 - 32 GB 1333 MHz DDR3 - AMD Radeon HD 6770M 512 MB

This is the BOM that i bought:
  • Dell Precision AMD FirePRO WX7100 8GB 308VY - V345 Ver 1.1 Ellesmere
  • a "new" used GPU heatsink with 3 pipes
  • epoxy glue (for odd sensor mod)
  • arctic mx-5 (for GPU)
  • k5-pro thermal pad replace (for vram, etc)
  • copper pads, if needed (different thickness) - i don't used :(
  • kapton tape (always useful)

I started the install procedure with the follow modifications:
  1. heatsink thickness reduction (see photo 01-A&B) "a dremel work", for a correct coupling with the video card 01-A.jpg01-B.jpg
  2. ODD sensor glued with epoxy glue (photo 02)

    02.jpg
  3. removal of the 4 threaded rings from the original (of WX7100) x-bracket (photo 03)
    03.jpg

So i started to install:
  1. Coupled the video card with the heatsink (+ arctic mx-5 for the GPU and + the k5-pro for all the other components)
  2. Connected the original GPU sensor (of the heatsink) to the motherboard
  3. All cables reconnected except for the SSD and ODD (power and data)
  4. USB key with linux ready to flash videocard.... inserted the key... (USB key boots on my macbook)
  5. .....but the system doesn't start.. iMac doesn't boot! (no boot chime) :O

So i removed the LCD panel, and turned on the system (always with SDD and ODD disconnected and the USB inserted):
  1. 2 of 4 leds turn on (first and second on, third and fourth off)
  2. no boot chime
  3. after a while the CPU fan starts to go very fast
  4. iMac don't boot from the USB and i can't flash the video card
  5. if i install the original video card (AMD Radeon HD 6770M 512 MB with his gpu sensor), iMac start and boot without any problems....

I think i wrong something... seems that iMac goes in protection mode...


Someone with more experience than me, has some suggestions or ideas??

thank you so much!


Attached some photos...
 

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