Can anyone suggest a Mac user group. Just got a free 2011 27" i 5 iMac that I may or may not install Linux on. I have already installed Linux on a Macbook, so am familiar with the hoops that need to be jumped through. This one gets stuck in the boot process before I get to entering the user name and password. I have a Linux disc for booting and installing on a Mac but am reluctant to do so at this point. I want to shut it down if possible with out pulling the plug.

Gets stuck in process of booting what, the installed MacOS?

Has it ever had its cooling system cleaned? Does its fan run? It could be overheating, in which case power switch or plug pulling is the only exit.

Why not boot your Linux installation media? It shouldn't do any writing to internal storage before telling the installer, after answering lots of questions, to go ahead and proceed to install. Once an installer is booted, you should be able to switch to a vtty (if necessary) to run some diagnostic utils, e.g. sensors.

You need to be very careful about booting Linux Live on a Mac, especially a distro that is not modified to boot and install on it. Doing so can mess up the mac install even if you are only booting to a live session.

I am finding out that the mac probably has a bad graphics card. $14 to about $200. The Mac's CPU runs the video up to a certain point where the graphics card takes over. Stalling before getting to login is a sign of that. Will try a few things to eliminate the graphics card. Any direction to a mac a reliable Mac user group would be appreciated.

External monitor worked for me when laptop lcd inverter board and lcd cable went bad on me.

This was not on a Mac laptop computer though.

I guess the vga port bypasses that.

How do you know that? A live distro will/should not even touch the built-in disk drive (only if you want to install it). Probably you can't boot it at all, but it should not harm any installed system.

From experience. Let me modify my statement. This was true with mid 2006 32bit/64bit MocBook with EFI. I think thats the right terminology. That Mac with 64bit Intel CPU would only run 32 bit OS. Why oh why do they do things like that! I have a Dell laptop that is like that as well. I think MacBook would no longer boot to Mac OS because the live session only partially booted, had to pull the plug which caused the MacBook to not boot to it's OS. Anyway you need a specially modified Linux OS to boot those machines. Do otherwise at your own risk. You can DIY or checkout Mattgradient.com and download one. Newer machines will boot linux no problem. I found several Mac Forums. Not booting to login indicates bad GPU. I booted the iMac to Live Mint Cinnamon 20.1 session. It came up with full video. Watched YouTube videos. System Settings > Hardware > Video indicates its running at 2560 X 1440 resolution so I assume the GPU is good Any other tests I can run on the GPU?

I did run lshw and xvinfo.

Sorry about late reply. Never got Email notice. Not in junk.

Which distro are you trying to use? I have a system pretty much identical to yours, but it is a 2012-vintage unit. The hardware is still good, but updates to the OS ended in 2018. crApple considers it to be junk... er, I mean EOL. It is not.

I installed Mint 20.3 and Slackware 15 on it (Slackware first). Only Mint was fully functional. Slackware had issues with ELILO, which I was able to work around, but sound didn't work. Mint has no issues whatsoever, and that is what I'm keeping on it. It installed no differently than on a standard Intel-based PC.

I've never tried to install another distro on it, so I have no opinion on them.

I don't know what Mac OS version is on it. I am running Mint 20.1 Cinnamon live session on it right now. I will install the latest Mint on it or dual boot Mint if I can get the Mac OS to load. Supposedly the Mac OS won't load to a login because the GPU is bad. I thought I had to have a Linux medium modified for Mac. I did have to do that for mid 2006 mac that had 64bit cpu but only ran 32 bit OS. Dell did that on one of their machines. Anyway the iMac booted to regular Mint OS.

I am currently in the process of stress testing the GPU to see if it is really 100% functional. Your 2012 is a much better machine. the Mid 2011's GPU had lots of failures. Apple rep;aced a lot of them. Replacement is 2 hour job. Used ones last 3 months that's $20 to $100. New from China is $200. Not able to find if that is New Old Stock that's going to fail or new and improved.

I will try the Mac system restore to see if that helps or reinstall the default OS online if Apple is willing. I am thinking there is a Mac GPU driver problem.

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