Okay, so you know that iMac (mid-2011 model) I rescued from a thrift store for fifteen dollars? After some struggling and a little panic about the screen not working (it was just a cable that disconnected, no biggie), I got it back up on its feet. Hooray for me!
There's just one problem, though. What the heck do I do with this thing? I gave some thought to turning it into an emulation station, but I'm not sure that a machine this old would be much good for 21st century console emulation (ie PS2, GameCube). I tried installing Dolphin for testing purposes, only to be told that the OS (El Capitan) was too old and that I'd need to download a legacy version instead; one that's likely less optimized and slower than the latest ones.
I've been doing some research and have discovered that this iMac can run a more modern OS, Catalina, with a patch. Would that newer operating system even be feasible on such an old system, though? Years ago, I bought a netbook that someone foolishly installed Windows 10 on, and it was dreadfully slow. (The previous owners put Windows 10 on a damn netbook. What were they thinking?!)
Also, I'm quickly discovering that Mac OS doesn't work the same way as Windows. When I downloaded and installed the Dolphin software, it just plopped it on the desktop, rather than letting me specify a folder and then creating a desktop shortcut to it. Is there a guide somewhere that would help guide me through the differences? Windows is intuitive for me after using it for a quarter of a century, but Mac OS, not so much. I think I'm going to need a Mac for Dummies book to really feel comfortable using this thing.
Thanks in advance for any help you can offer!
EDIT: This wasn't mentioned in the original post, but I wanted to clarify that I've already put an SSD into this system. It's the reason I had to open it up in the first place... and then put in the terrible, terrible screen screws. (Ugh, I'm still having flashbacks.)
I think it's got 8 gigs in there already... I'll need to look at the About file to confirm it. I may need more than that? What's this thing top out at? 16GB, 32GB?
Apple tech specs online says that it'll support up to 16GB -- but sometimes their spec sheets lowball the actual compatibility. At any rate, you can be sure that it'll accept at least that much. (Source)
And maxing out the RAM is always better for performance, regardless of whether you're using macOS, Windows or Linux. (This is doubly true with older hardware, such as what you've found.) The question isn't, is more RAM a good idea... it's, is more RAM worth the cost. And with a 16GB RAM kit for that system going for about $16 on Amazon, I'd personally say go for it. (Double-check that I've found the right link for you, of course, just in case.)
Expanding on that, the official maximum is whatever was available in 2011 (or perhaps even a year earlier). Once a product is shipped, they don't go back and test it with newer third party components (unless it's a Mac Pro).
These days, it should be able to run 32GB - there are larger chips available that are compatible. I'd upgrade it to at least 16GB - you want as many files on disk in RAM cache as possible.
Do some research though - because aside from having the right specs you need to worry about the physical size too. Sometimes the larger capacity chips are also a few millimetres larger and outside of the Mac Pro Apple isn't known for leaving extra empty air space around internal components. In fact Steve Jobs famously threw an expensive prototype in a fish tank to test someone's claim that it couldn't be made any thinner - bubbles came out, and he ripped the designer to shreds for lying.
That story was around the same time as OP's iMac was designed by the way. Might have been designed by the same engineer... who I'm pretty sure learned a lesson and stopped designing empty space into his products. If you want a future proof Mac, you buy a Mac Pro. Those do have plenty of room for upgrades: