iMac mid 2011 hard drive replacement with SSD drive

Mac mini's (the new M1 mode) is a rocket and a very good option. You can use your iMac's keyboard and mouse, you only need a display. An external display can be found at Costco and you can usually find one for about $150 that works just fine.

Buy the MM with 16GB of RAM and the largest SSD (1TB is fine for most users) and you will have a dandy little Mac!

IMHO it is not worth it, to put a SATA cable upgrade kit and an SSD into a 9+ year old iMac. Plus to make matters worst, the iMac can only run up to 10.13 High Sierra, which will likely be dropped from future Security Update sometime in 2021.

You're welcome.

FWIW to some degree I feel your pain, because in addition to a couple of newer Mac's running Mojave and Catalina. I also have a couple of older Mac's (a 2010 and a 2011) running High Sierra, that will need to replaced sometime in the near future.

OK.... Two issues, memory and hard drive...

Memory...

First, look under "About This Mac", then "Memory" and determine if you have four 2 gig chips, or two 4 gig chips...

Adding more memory is possible, on the 2010 with a Core I3 processor, 16 gig is the max. four 4 gig chips...

On the 2011 Core I5 and Core I7, 32 gigs is the max. Four 8 gig chips...

I get my memory from Data Memory Systems dot Com, Other World Computing is another good source...

I recommend at least 16 gigs...

Hard drive...

The 2010 and 2011 hard drives had thermal sensors built into the drives. Other World Computing has external replacement sensors, allowing you to use any drive...

https://eshop.macsales.com/shop/imacdiy/

(Note that the 2010 iMacs have a SATA III interface, 6 gigabytes a second, but a SATA II drive, 3 gigabytes a second...)

These old iMacs are not hard to take apart, look on ifixit dot com for directions.

Look on New Egg for hard drives, I recommend Western Digital Black platter drives, and Samsung EVO SSD's

https://www.newegg.com/black-wd4005fzbx-4tb/p/234-000G-000W6?Description=western%20digital%20black&cm_re=western_digital%20black-_-234-000G-000W6-_-Product

https://www.newegg.com/p/pl?d=samsung+860+evo

If you run a 2.5 SSD, you will need a 2.5 to 3.5 adapter...

https://eshop.macsales.com/item/NewerTech/ADPTADRV/?GCh19-Ax_EAQYAiABEgJxhfD_BwE&gclsrc=aw.ds

I am running 20 gigabytes with a 4 gig platter drive, plenty fast...

One option to consider is that you could get an external USB bus powered laptop sized SSD drive, it will be small, compact, quiet, and fast. Use Carbon Copy Cloner to copy the internal drive to the external, and set the external as your new startup disc in System Preferences. When you retire the machine, you can still use that drive with a new computer.