This website greatly simplies the huge list of options. But regardless, this upgrade can be complex: need to load software/firmware into multiple pieces of the hardware and can't do it while macOS is running in some simple app. If just want to just start and see what happens. Just be prepared to have to do some reading when something fails and getting blocked. So to start, just do the following
These iMacs are largely obsolete as Apple stopped operating system support long ago (High Sierra - HS) and no major browsers supports HS for a few years now.
Website is made for newbies wanting to make these old iMacs that are perfectly good still able to run the latest macOS well at a fairly low cost. Just keep these beautiful machines useful for daily personal computing needs. Goal is the reduce the vast combinations and provide a relatively simple and not error prone sequence to understand and follow. This guide isn't for those who looking to make lots of mods, special cases, or highest graphics performance.
There are vast amounts of scattered online information to surf through because these efforts are originally development efforts and all the partial dev steps and partial success are archived on internet in forum posts, youtube videos and even older guides. So time and progress has made some area obsolete while other area remain criticaly important (This is nature of constantly changing software). So someone/guide need to gradually explain and point the way. Preferably closer up to date.
NOTE : There is no short cut to understanding fair bit of stuff. No magic load this software run it and it will complete and do everything by itself. This is because need to patch how a computer and its graphics card communicate with each other during booting (boot code) thus multiple pieces of software need to be patched. Boot code insertion can not be done with full OS running so its usually less user friendly tools. This guide hopefully will help with understanding the information efficiently at a high level big picture and guidance towards the necessary details.
It is possible to run later macOS successfully without metal GPU upgrades with OCLP. See here
Most of the complexity is from making and insert custom boot code for the CPU (OCLP) and GPUU (vBIOS) These are 2 big steps for new comers. Can certainly be challenging depending if having more advanced software firmware installation skills.
AliExpress has sellers sell pre-flashed vBIOS most common choice GPU cards. This bypasses one of the big learning steps. See here
It is most likely the bigger faster GPU as they run hotter. Consider buying a smaller OEM GPU from an iMac. People who have successfully upgraded to metal GPU are selling their older (and working if they are honest, look at their ratings) one on ebay. For example, an HD 5750 is a larger card that often fails, HD 5670 is 1/2 - 2/3 performance smaller card which probably last longer.
Using OEM GPU with OCLP Big Sur, can generally have fairly good UI experience with couple of tweaks and works well. Can at least run the latest modern browsers as they all have obsoleted High Sierra long ago. link
Big Sur with some transparency tweaks maybe good enough for many casual users!
Learn 2 big steps at once is likely failure. Consider first learn OCLP with a working OEM GPU (say upgrade to Big Sur first mentioned just above). Once experienced with this, then attempt pre flashed metal GPU, finally if necessary, learn to flash your own GPU
Most don't tell you the multiple failure points.
OCLP is relatively easy when it doesn't encounter a failure requiring workaround. I've done OCLP installation many times and still regularly encounter installation errors (maybe 25%?).
OCLP also limits easy migration from one Mac to another. Assume manual migration (manually transfer important files, reload apps)
GPU vBIOS flashing has failure points too. Out of 3 iMacs, I encountered one failure exception from the simpler flash process and had to go to a harder one (requires soldering even haha)
There are only 2-3 easier choices that can be acquired easily (depending on which one) at reasonable cost. Also pre-flashed cards have some risks ( link )
2009-2010 iMac 11,x and iMac 10,x can be upgraded with lowest cost AMD M4000 and slightly higher cost M5100 (made ~2012-13)
2011 is a bigger challenge to upgrade for lower cost because the lower cost AMD cards don't work and require newer and pricier AMD WX4130 (made ~2016-17) Alternative is nVidia Kepler cards such as K1100M but only fully compatible up to Big Sur (still much better than High Sierra with latest browser support)
If 2009-2010. Good candidate for +Metal GPU upgrade and upgrade to macOS Sonoma. I'm typing up this guide on such machine now. Works quite well. Capable daily driver and quite fast!
The M4000, M5100 and WX4130 cards are the most robust / lowest cost options. There are other cards of course but complexity increase quickly and left after gaining expertise
Maybe your motivation is to save your own iMac or maybe some in your area and make a little pocket money. Its not a profitable operation to feed a family but fun to tinker for a good cause. Save the iMacs and make a little pocket change :)
Often these iMacs are free or < $50. Some with failed GPUs (original GPU runs hot) Additional $50 (GPU card, SSD, extra 4GB RAM to make 8 total) turns these into quite usable machines. 27" iMacs are bigger screen than even the latest M3 iMacs. And they are still quite fast.
There are probably many devs to thank and I don't even know them all haha. I'll just list a few I've encountered in this and past obsoleted Mac upgrade efforts
dosdude1 and other earlier guys kick started all this a few years back. I still remember MacPostFactor haha (old tool to upgrade even older Macs) Now I see him solving the next Mac longivity problem (solder upgrade/replace SSDs haha)
@MichaelDT for his original post and now 20k+ long thread haha
@Ausdauersportler for doing most (maybe all? haha) the AMD vBIOS we need to flash
@xanderon for making a GPU flash tool and @The_Croupier for adding the AMD bits
@internetzel for later model AMD GPU vBIOS
EVERYONE at OCLP! haha
Probably tons of people I don't know of that did various foundational work
I'm sure this is way incomplete list of credits as I am not long term dev on this stuff. Those people would be able to tell you who are all thats involved!
If you find this info useful in keeping these iMacs quite useful and less landfill. Consider donating to the good folks and effort listed in the credit above. They did all the work, this website just merely provide an end user effort of using their work.
https://dortania.github.io/OpenCore-Legacy-Patcher/DONATE.html
https://forums.macrumors.com/members/ausdauersportler.1199136/#about
I see tons of 2012+ iMacs for sale on FB Marketplace and CL for cheap due to cracked screens.. These screens are double sided glued down and must be cut open to change the HDD to SSD for faster performance.
ALL replacement tapes sold on Amazon, ifixit, and ebay are the culprit. They look the part but am not quality high bond tapes made by likes of 3M and Tesa. Tons of low cost counterfeiters likes to print these high end tape manufacturer's logos on their fake tapes.Am current actively searching for a source for good cleaning procedure and replacement tape.
Can reach me at @howardc64 on macrumors.com
My contact is not for direct help or tech support. Please use Post #1 thread AND this guidance website and some DIY research. Contact is here if want to collaborate, improve information etc.