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Upgrade Mid 2011 iMac 21.5 beyond High Sierra?

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Warped9

macrumors 68000
Original poster
Oct 27, 2018
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Brockville, Ontario.
Here is the thing. I have a mid 2011 21.5 iMac (since new) and over the years I have upgraded it to 32GB RAM, Samsung EVO 860 SSD and an Intel-Core i7 2600S. And I’m stuck at Mac OS High Sierra.

I cannot speak to the accuracy, but I have heard it is actually possible to upgrade an iMac such as mine beyond High Sierra, possibly up to Catalina. I’d like to know if thats at all true and if so then how could it be done?

I have contemplated getting a new M1 24 iMac, but presently my 2011 iMac runs flawlessly with no issues whatsoever. As such I could wait until the current 24 gets its first upgrade to M2 (or whatever) next year or so.

I’m also wondering if it’s worth considering upgrading my video card although that isn’t a priority.
 
Yes, you can run Mojave or even Catalina. Check out dosdude1's website, particularly the patches he made for older Macs so that they can run "newer" macOS versions than they were made for. Link: http://dosdude1.com/software.html
Read the info that relate to your particular iMac and if his patcher supports it. My guess is that it does. Follow his instructions... I ran his patched version of Mojave on my late 2009 iMac for a couple years. Great patcher, one of the best for sure. Dosdude1 is the best!
 
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You mentioned you'll buy a new iMac next year. Hence and frankly if I were you, I won't bother doing anything to extend its service for only one more year.

2011 iMac is rightly still a capable but a ten-year old machine. Some of its internal components are possibly at the brink of break-down. Keep it as is. You might squeeze a few more years of functional life. Performing any non trivial surgery..I'm afraid you'll easily accelerate the death of some of its components. Unless you're very delicate at your craftsmanship.

You'll need a Polaris-class GPU which is hard to come by. Spending a huge sum to acquire one is simply ludicrous. Nvidia then? Doable but I would rule them out right away. You also need to replace WiFi/bluetooth combo card. And that's not the end of your job to keep it running.

Once you drill down this rabbit hole, it's no different from operating a Hackintosh. I know I know..perhaps it's still a genuine Mac that makes ppl feel different. But in terms of fiddling, tinkering, resolving new issues with major macOS updates and releases, it's the same.

Unless fiddling, tinkering, and talking about what you've achieved is part of your daily enjoyment of operating a computer, it's wise to let go the idea.

Peace
 
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Those 2011 iMacs run AMD GPU's (5xxx or 6xxx), and Dosusde's site specifically states that there will be no hardware acceleration with those cards.

So yes, Catalina will run, but it will run close to unusable slow.

He advises to upgrade the GPU to a metal capable card to allow the use of hardware acceleration and get a normal working card.

So, there is one veeery long thread on here (the longest of all threads :) ), read the first post very good, it has all the info on upgrading the GPU, flashing bios, which cards will give you bootscreen and/or brightness control after the bios flash etc.

With the 21.5" you are lmited in which cards you can use due to te lower power output of the power supply, compared to a 27" model.

If you decide to upgrade the GPU and it works out, you might also want to read up on using OpenCore to upgrade your machine to more recent OS versions, it's more complicated, but you'l end up with a machine that Aple will thing is a more recent version, resulting in automatic updates workin correctly, als for example upgrading to Big Sur, and likely even automatically upgrading to Monterey when it comes out of Beta.

Will also depend om which GPU you end up using, as for example Apple stopped using Nvidia gpu's in 2015, so if they decide that 2015 machines (macbooks, iMacs, ...) will not get Monterey, than your OpenCore machin also will not be able to upgrade to Monterey as they will drop the drivers (kexts) for Nvidia cards out of it completely.

All the above will require some decent sckills, bot hardware replacement wise, research, software tinkering, so as a hobby, yes go for it, on a machine you really need to use on a daily base for work/school/whatever, better forget about it then....
 
I just (last night) upgraded my 2011 27” to Big Sur using OpenCore. I created a separate partition on the 2TB internal SSD, so I could test things without risking the whole system and having to do a lengthy restore if things didn’t work out. So far things seems good, a couple of bugs with Maps and Podcasts getting stuck on launch, but these are apparently fixable. Pretty cool really, considering the graphics card is the stock base model and non-Metal compatible. Definitely worth a try, here’s a link to the video guide I used:

 
So swapping out the GPU would be a necessity and it isn’t a walk in the park. Also I realy have no complaint with my factory AMD Radeon HD 6750M.

I upgraded my iMac because at the time it was more cost effective than buying a new one with specs I wanted. That and I knew a redesign was imminent (eventually) and it has to be at least as capable as what I have presently with its upgrades. Everything I’ve seen and read looks to affirm the present M1 24 iMac with 16GB RAM should run circles around my current machine. The next 24 upgrade or the forthcoming M1X 27 replacement will do even better.

So, it doesn’t look to be cost effective to tinker beyond what I have already. My best course looks to be keep using my machine as is until I see whats available next year, then take the plunge and hope it lasts perhaps another ten years. Even though I’m stopped at High Sierra I have no issues and I’m not desperate for a new machine—not a bad position to be in.

Still, thank you everyone for the feedback and advice. If nothing else I am now a bit more educated on the subject.
 
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Warped9 said:
So swapping out the GPU would be a necessity and it isn’t a walk in the park. Also I realy have no complaint with my factory AMD Radeon HD 6750M.

I upgraded my iMac because at the time it was more cost effective than buying a new one with specs I wanted. That and I knew a redesign was imminent (eventually) and it has to be at least as capable as what I have presently with its upgrades. Everything I’ve seen and read looks to affirm the present M1 24 iMac with 16GB RAM should run circles around my current machine. The next 24 upgrade or the forthcoming M1X 27 replacement will do even better.

So, it doesn’t look to be cost effective to tinker beyond what I have already. My best course looks to be keep using my machine as is until I see whats available next year, then take the plunge and hope it lasts perhaps another ten years. Even though I’m stopped at High Sierra I have no issues and I’m not desperate for a new machine—not a bad position to be in.

Still, thank you everyone for the feedback and advice. If nothing else I am now a bit more educated on the subject.
Click to expand...
Upgrading the graphics is not a necessity if you want to run Big Sur, see my post above. I have seen a few minor graphical glitches since I installed it, but nothing that really affects actual utility. As I said, try it on a partition and you have nothing to lose.
 
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Here is one other small wrinkle on my iMac. The original 500GB hard drive is still in the machine. If I had swapped it out for the new SSD I also would have had to install a thermal cable or the fans would have gone nuts thinking the machine was overheating (or something to that effect). The guy who did the work for me suggested leaving the HDD in place and install the SSD behind my optical drive where there was sufficient space and an appropriate cable was already in there waiting to be used (presumably for any factory installed SSD?). He could have removed the optical drive permanently, but he found it wasn’t necessary to lose it.

Once the install was done I simply booted from the SSD and, voila!, instantly vastly better performing machine along with the i7 and 32GB RAM.
 
Warped9 said:
Here is one other small wrinkle on my iMac. The original 500GB hard drive is still in the machine. If I had swapped it out for the new SSD I also would have had to install a thermal cable or the fans would have gone nuts thinking the machine was overheating (or something to that effect). The guy who did the work for me suggested leaving the HDD in place and install the SSD behind my optical drive where there was sufficient space and an appropriate cable was already in there waiting to be used (presumably for any factory installed SSD?). He could have removed the optical drive permanently, but he found it wasn’t necessary to lose it.

Once the install was done I simply booted from the SSD and, voila!, instantly vastly better performing machine along with the i7 and 32GB RAM.
Click to expand...

With this kind of skill, you'd better have someone else do the job for you.
Installing Big Sur on a partition of you main disk is not a smooth-as-silk process. It's even riskier when you mess-up with the file system. Back-up your data and be prepared for the worst case scenario.
 
Warped9 said:
Here is one other small wrinkle on my iMac. The original 500GB hard drive is still in the machine. If I had swapped it out for the new SSD I also would have had to install a thermal cable or the fans would have gone nuts thinking the machine was overheating (or something to that effect). The guy who did the work for me suggested leaving the HDD in place and install the SSD behind my optical drive where there was sufficient space and an appropriate cable was already in there waiting to be used (presumably for any factory installed SSD?). He could have removed the optical drive permanently, but he found it wasn’t necessary to lose it.

Once the install was done I simply booted from the SSD and, voila!, instantly vastly better performing machine along with the i7 and 32GB RAM.
Click to expand...
Bad info! No need to keep the Original HDD.
Especially for the "upgraders", keeping the HDD on top of the extra SSD seriously limits the avalable power for a faster Graphics card!

You can perfectly take out the HDD and replace with an SSD, only then you would need to use a free program called Macs Fan Control.
Works perfect!

There are a few other solutions like buying and installing the T° sensor, what you call "thermal cable" (which normally is built in an Apple version HDD), OWC sells them for about 40 bucks.
A bit pricey, but works!
 
Warped9 said:
Here is one other small wrinkle on my iMac. The original 500GB hard drive is still in the machine. If I had swapped it out for the new SSD I also would have had to install a thermal cable or the fans would have gone nuts thinking the machine was overheating (or something to that effect). The guy who did the work for me suggested leaving the HDD in place and install the SSD behind my optical drive where there was sufficient space and an appropriate cable was already in there waiting to be used (presumably for any factory installed SSD?). He could have removed the optical drive permanently, but he found it wasn’t necessary to lose it.

Once the install was done I simply booted from the SSD and, voila!, instantly vastly better performing machine along with the i7 and 32GB RAM.
Click to expand...
For the guy who did the upgrade for you and advised keeping the HDD, give him a good slap on the wrist as that was bad advise! The original HDD's generate large amounbts of heat which is detrimental to the gpu and other components. Replacing the HDD by an SSD on these machines is one of the best mods possible, not only to vastly improve performance but also to reduce heat and at least give that Radeon GPU a little more 'breathing space'. Agreed an SSD will require the work-around to keep the fans from going berserk, an easy fix with either the new temp sensor or using Macs Fan Control.
 
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Berenod said:
Bad info! No need to keep the Original HDD.
You can perfectly take out the HDD and replace with an SSD, only then you would need to use a free program called Macs Fan Control.
Click to expand...
So OP was not given bad advice, then. Without the HDD the machine doesn't work properly unless you install third party apps to control the fans. Strictly speaking the OP's tech was completely correct.
 
I had the same model as you, a 2011, 21inch iMac, and I have upgraded the CPU to 2600s, 32GB RAM, 2TB EVO 860 SSD, and K2100M GPU, and with Open Core, I am able to run Monterey OS on it without issue.
 
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ElCani said:
I just (last night) upgraded my 2011 27” to Big Sur using OpenCore. I created a separate partition on the 2TB internal SSD, so I could test things without risking the whole system and having to do a lengthy restore if things didn’t work out. So far things seems good, a couple of bugs with Maps and Podcasts getting stuck on launch, but these are apparently fixable. Pretty cool really, considering the graphics card is the stock base model and non-Metal compatible. Definitely worth a try, here’s a link to the video guide I used:

Click to expand...
@ElCani Is this still working for you? There is a more recent video from eailer this year and it looks a little easier to accomplish.
 
bijianWu said:
I had the same model as you, a 2011, 21inch iMac, and I have upgraded the CPU to 2600s, 32GB RAM, 2TB EVO 860 SSD, and K2100M GPU, and with Open Core, I am able to run Monterey OS on it without issue.
Click to expand...
I'm trying to an upgrade using the same K2100M GPU, have upgraded RAM but original HDD. Running High Sierra on the original GPU - how did you update the iMac so it would recognise the GPU - I believe I need to flash the GPU BIOS, did you do that? All because the kid needs metal support to run her school stuff and fave game! Any pointers to good instructions appreciated. My brain is fried going through everything I can find.
 
Hello, I've an iMac 12,1 21,5" with NVIDIA K2100M, BCM943602CDP, CRUCIAL MX500 1TB (with OWC Sensor) and running the latest version of Ventura... everything seems working very well... every app, every site and every setting except of PowerNap... I don't have this option in my macOS... how can I do? Does it exist a patch? Thank youuuu
 
I'm waiting for the $$$ to fall some, then I'll locate something a touch newer. Being in the same situation as Bartaz.. I'll wait awhile since what is on hand, does well enough for the time being (and being paid for helps). Hopefully, someone comes up with a simple patch that allows me to keep kicking the can. pc
 
njones254 said:
I'm trying to an upgrade using the same K2100M GPU, have upgraded RAM but original HDD. Running High Sierra on the original GPU - how did you update the iMac so it would recognise the GPU - I believe I need to flash the GPU BIOS, did you do that? All because the kid needs metal support to run her school stuff and fave game! Any pointers to good instructions appreciated. My brain is fried going through everything I can find.
Click to expand...
you need to flash the GPU BIOS, then it will work, can you find tons of videos on the Youtube that shows you how to do it, I bought the GPU from aliexpress, and the seller has already flashed the GPU's BIOS
 
Bartaz said:
Hello, I've an iMac 12,1 21,5" with NVIDIA K2100M, BCM943602CDP, CRUCIAL MX500 1TB (with OWC Sensor) and running the latest version of Ventura... everything seems working very well... every app, every site and every setting except of PowerNap... I don't have this option in my macOS... how can I do? Does it exist a patch? Thank youuuu
Click to expand...
What about the Weather widget? Can you enter locations other than Cupertino?
 
Good evening, I do not know if this old iMac is still relevant, but I will post it. My old iMac 2011 21in upgraded with a Nvidia 3GB 770m is running Sequoia 15.0.1 (24A348) very well. It runs better than Sonoma which lagged. I had installed Windows 11, but the missing drivers was a hassle.



Screenshot 2024-10-24 at 5.10.25 PM.png



Screenshot 2024-10-24 at 4.54.55 PM.png
 
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