See which Macs will -- and won't -- work with MacOS - CNET
See which Macs will -- and won't -- work with MacOS - CNET
Identify your iMac model - Apple Support
Some Users Report macOS High Sierra Gives Old Macs Better Performance - The Mac Observer
21.5” iMac 2009 for Sale in Long Beach, CA - OfferUp
macOS High Sierra On A 2009 Imac Core 2 Duo? A Retro Adventure :o) - YouTube
OWC DIY Kit for 2012 - 2019 21.5" iMac's factory... at MacSales.com
Apple MC309LL/A 21.5" iMac Computer Core i5 2.7 GHz 4GB RAM 1TB HD Mid-2011 | RecycledGoods.com
Apple iMac A1224 Mid 2009 20in 2.26GHz 4GB DDR3 RAM 250GB HDD EL-CAPITAN 618996989331 | eBay
Apple iMac Mid 2011 A1311 21.5" Intel Core I7 2.8ghz 4gb RAM 1tb HDD OS X Sierra for sale online | eBay
iMac 27" 2.8GHz (Late 2009) | mac of all trades
SOLVED: Upgrade OS to High Sierra? - iMac Intel 20" EMC 2316 (Edu) - iFixit
What to Do if Your Mac Can't Run macOS Sierra - The Mac Security Blog
How to Prepare Your Mac for macOS High Sierra - The Mac Security Blog
iMac (Early 2009) | Low End Mac
Apple iMac 21.5-inch Late 2009 3.06GHz Intel Core 2 Duo (MB950LL/A) – UNICOM, Inc.
Retro Review: 2009 Mac Pro in 2022 | iMore
